Here follows a couple of styles. All used with, but most not limited to, a MVVM desig patten.

First a text style

<ResourceDictionary x:Class="foo.View.Styles.TextStyle"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
    <Style x:Key="DefaultTextStyle" TargetType="{x:Type TextBlock}">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
        <Setter Property="HorizontalAlignment" Value="Stretch"/>
        <Setter Property="FontSize" Value="12"/>
        <Setter Property="FontWeight" Value="Bold"/>
        <Setter Property="FontFamily" Value="Verdana"/>
        <Setter Property="Foreground" Value="#FF17447E"/>
        <Setter Property="TextWrapping" Value="Wrap"/>
        <Setter Property="TextAlignment" Value="Left"/>
    </Style>
</ResourceDictionary>

Here is a style for a image that will fade in i half a second, and after 1,5 second it will fade out in 1 second

<ResourceDictionary x:Class="foo.View.Styles.FadeOutImageStyle"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">
    <Style x:Key="DefaultFadeImageStyle" TargetType="{x:Type Image}">
        <Style.Triggers>
            <Trigger Property="IsVisible" Value="True">
                <Trigger.EnterActions>
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetProperty="Opacity" From="0.5" To="1.0" BeginTime="0:0:0" Duration="0:0:0.5"/>
                            <DoubleAnimation Storyboard.TargetProperty="Opacity" From="1.0" To="0.0" BeginTime="0:0:1.5" Duration="0:0:1"/>
                        </Storyboard>
                    </BeginStoryboard>
                </Trigger.EnterActions>
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

and of course can be used like

Style="{StaticResource DefaultFadeOutImageStyle}

Then a style for a plain squre ProgressBar without any glossy effects or gradient colors. This one I found here:

http://stackoverflow.com/questions/12871978/removing-gloss-from-progressbar

<ResourceDictionary x:Class="foo.View.Styles.ProgressBarStyle"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
    <Style x:Key="DefaultProgressBar" TargetType="{x:Type ProgressBar}">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ProgressBar">
                    <Border BorderBrush="Transparent" BorderThickness="0" Background="Transparent" CornerRadius="0" Padding="0">
                        <Grid x:Name="PART_Track">
                            <Rectangle x:Name="PART_Indicator" HorizontalAlignment="Left" Fill="#00DB69"/>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

Here is a style for WPF ToolTip that will look something like this:

<ResourceDictionary x:Class="foo.View.Styles.ToolTipStyles"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">
    <Style x:Key="{x:Type ToolTip}" TargetType="ToolTip">
        <Setter Property="MinHeight" Value="100"/>
        <Setter Property="Placement" Value="Right"/>
        <Setter Property="HasDropShadow" Value="False"/>
        <Setter Property="Visibility" Value="{Binding Path=ToolTipVisible}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ToolTip">
                    <Border BorderBrush="White" BorderThickness="4" Width="190" Height="{Binding Path=Height}" Background="{Binding Path=ToolTipBackgroundColor}" MinHeight="100">
                        <DockPanel VerticalAlignment="Top">
                            <TextBlock DockPanel.Dock="Top" 
                                       Text="{Binding Path=DescriptiveText}" 
                                       Visibility="{Binding Path=DescriptiveTextVisibleInToolTip}"
                                       FontSize="14" 
                                       FontWeight="Bold" 
                                       FontFamily="Verdana" 
                                       Foreground="White" 
                                       Margin="5" 
                                       TextWrapping="Wrap" 
                                       TextAlignment="Justify">
                                <TextBlock.Style>
                                    <Style TargetType="TextBlock">
                                        <Style.Triggers>
                                            <Trigger Property="Text" Value="{x:Null}">
                                                <Setter Property="Visibility" Value="Collapsed"/>
                                            </Trigger>
                                            <Trigger Property="Text" Value="">
                                                <Setter Property="Visibility" Value="Collapsed"/>
                                            </Trigger>
                                        </Style.Triggers>
                                    </Style>
                                </TextBlock.Style>
                            </TextBlock>
                            <TextBlock DockPanel.Dock="Top" Text="{Binding Path=ToolTip}" FontSize="10" FontWeight="Bold" FontFamily="Verdana" Foreground="White" Margin="5,0,5,0" TextWrapping="Wrap" TextAlignment="Justify"/>
                            <TextBlock/>
                        </DockPanel>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <EventTrigger RoutedEvent="ToolTip.Opened">
                <BeginStoryboard>
                    <Storyboard>
                        <DoubleAnimation Storyboard.TargetProperty="Width" From="0.0" To="200" Duration="0:0:.5"/>
                        <DoubleAnimation Storyboard.TargetProperty="Opacity" From="0.0" To="1.0" Duration="0:0:1"/>
                    </Storyboard>
                </BeginStoryboard>
            </EventTrigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

A DataGrid style that wiil make the DataGrid look like this:

<ResourceDictionary x:Class="foo.View.Styles.DataGridStyles"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">
    <Style x:Key="DefaultSettingsDataGrid" TargetType="{x:Type DataGrid}">
        <Setter Property="IsEnabled" Value="{Binding Enable}"/>
        <Setter Property="Width" Value="{Binding DataGridWidth}"/>
        <Setter Property="HorizontalAlignment" Value="Left"/>
        <Setter Property="AlternatingRowBackground" Value="Beige"/>
        <Setter Property="AlternationCount" Value="2"/>
        <Setter Property="CanUserAddRows" Value="False"/>
        <Setter Property="CanUserDeleteRows" Value="False"/>
        <Setter Property="CanUserReorderColumns" Value="False"/>
        <Setter Property="CanUserResizeColumns" Value="False"/>
        <Setter Property="CanUserResizeRows" Value="False"/>
        <Setter Property="CanUserSortColumns" Value="False"/>
        <Setter Property="AutoGenerateColumns" Value="False"/>
        <Setter Property="HeadersVisibility" Value="None"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
        <Setter Property="TextBlock.FontFamily" Value="Calibri"/>
        <Setter Property="TextBlock.FontSize" Value="14"/>
        <Setter Property="TextBlock.FontWeight" Value="Bold"/>
        <Setter Property="TextBlock.Foreground" Value="Black"/>
        <Setter Property="TextBlock.TextWrapping" Value="Wrap"/>
        <Setter Property="TextBlock.VerticalAlignment" Value="Center"/>
        <Setter Property="GridLinesVisibility" Value="None"/>
        <Setter Property="BorderBrush" Value="#FF009CDD"/>
        <Setter Property="BorderThickness" Value="3"/>
        <Style.Resources>
            <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Transparent" />
            <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="Transparent" />
            <SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black" />
            <SolidColorBrush x:Key="{x:Static SystemColors.ControlTextBrushKey}" Color="Black" />
        </Style.Resources>
        <Style.Triggers>
            <Trigger Property="IsVisible" Value="True">
                <Trigger.EnterActions>
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetProperty="Opacity" From="0.0" To="1.0" Duration="0:0:0.8"/>
                        </Storyboard>
                    </BeginStoryboard>
                </Trigger.EnterActions>
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

 A ComboBox, that look like this:

<ResourceDictionary x:Class="foo.View.Styles.FlatComboBoxStyles"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">
    <Style x:Key="FlatComboBox" TargetType="{x:Type ComboBox}">
        <Setter Property="HorizontalAlignment" Value="Stretch"/>
        <Setter Property="HorizontalContentAlignment" Value="Right"/>
        <Setter Property="VerticalAlignment" Value="Top"/>
        <Setter Property="MinWidth" Value="100"/>
        <Setter Property="UIElement.SnapsToDevicePixels" Value="True"/>
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
        <Setter Property="TextElement.Foreground" Value="Black"/>
        <Setter Property="FrameworkElement.FocusVisualStyle" Value="{x:Null}"/>
        <Setter Property="BorderBrush" Value="Transparent"/>
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="Background" Value="Transparent" />
    </Style>
</ResourceDictionary>

Now this is a bit more complex. I don't know if it could be done more elegantly.

Obvious I found this style somewhere, but unfortunately I’ve forgotten where. Sincere apologies to the author.

Here is what the vertical ScrollBar that will look like this:

This style is only for a vertical ScrollBar:

<ResourceDictionary x:Class="foo.View.Styles.ScrollViewerStyle"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">
    <Style x:Key="DefaultScrollViewer" TargetType="{x:Type ScrollViewer}">
        <Setter Property="VerticalScrollBarVisibility" Value="Auto"/>
        <Setter Property="HorizontalScrollBarVisibility" Value="Hidden"/>
        <Setter Property="Background" Value="Transparent"/>
    </Style>

    <!-- SrollViewer ScrollBar Repeat Buttons (at each end) -->
    <Style x:Key="ScrollBarLineButton" TargetType="{x:Type RepeatButton}">
        <Setter Property="SnapsToDevicePixels" Value="True"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type RepeatButton}">
                    <Border Name="Border" Margin="0" CornerRadius="0" Background="#FF009CDD" BorderThickness="1" BorderBrush="White">
                        <Path HorizontalAlignment="Center" VerticalAlignment="Center" Fill="#FF009CDD" Data="{Binding Path=Content, RelativeSource={RelativeSource TemplatedParent}}" />
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsPressed" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="#FF009CDD" />
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="Foreground" Value="Gray"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <!-- SrollViewer ScrollBar Repeat Buttons (The part in the middle, not the thumb the long area between the buttons ) -->
    <Style x:Key="ScrollBarPageButton" TargetType="{x:Type RepeatButton}">
        <Setter Property="SnapsToDevicePixels" Value="True"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type RepeatButton}">
                    <Border Background="Transparent" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    <!-- ScrollViewer ScrollBar Thumb, that part that can be dragged up/down or left/right Buttons -->
    <Style x:Key="ScrollBarThumb" TargetType="{x:Type Thumb}">
        <Setter Property="SnapsToDevicePixels" Value="True"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Focusable" Value="false"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Thumb}">
                    <Border CornerRadius="0" Background="{TemplateBinding Background}" BorderThickness="1" BorderBrush="White"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <ControlTemplate x:Key="VerticalScrollBar" TargetType="{x:Type ScrollBar}">
        <Grid >
            <Grid.RowDefinitions>
                <RowDefinition MaxHeight="18"/>
                <RowDefinition Height="0.00001*"/>
                <RowDefinition MaxHeight="18"/>
            </Grid.RowDefinitions>
            <Border Grid.RowSpan="3" CornerRadius="0" Background="White" />
            <RepeatButton Grid.Row="0" Style="{StaticResource ScrollBarLineButton}" Height="18" Command="ScrollBar.LineUpCommand" Content="M 0 4 L 8 4 L 4 0 Z" />
            <Track Name="PART_Track" Grid.Row="1" IsDirectionReversed="true">
                <Track.DecreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageUpCommand" />
                </Track.DecreaseRepeatButton>
                <Track.Thumb>
                    <Thumb Style="{StaticResource ScrollBarThumb}" Margin="0,0,0,0" Background="#FF009CDD"/>
                </Track.Thumb>
                <Track.IncreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageDownCommand" />
                </Track.IncreaseRepeatButton>
            </Track>
            <RepeatButton Grid.Row="3" Style="{StaticResource ScrollBarLineButton}" Height="18" Command="ScrollBar.LineDownCommand" Content="M 0 0 L 4 4 L 8 0 Z"/>
        </Grid>
    </ControlTemplate>
    <!-- Style for overall  ScrollBar -->
    <Style x:Key="{x:Type ScrollBar}" TargetType="{x:Type ScrollBar}">
        <Setter Property="SnapsToDevicePixels" Value="True"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Style.Triggers>
            <Trigger Property="Orientation" Value="Vertical">
                <Setter Property="Width" Value="18"/>
                <Setter Property="Height" Value="Auto" />
                <Setter Property="Template"
                        Value="{StaticResource VerticalScrollBar}" />
            </Trigger>
        </Style.Triggers>
    </Style>

    <!-- Style for overall  ScrollViewer -->
    <Style x:Key="FavsScrollViewer" TargetType="{x:Type ScrollViewer}">
        <Setter Property="OverridesDefaultStyle" Value="True"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollViewer}">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="Auto"/>
                            <ColumnDefinition/>
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition/>
                            <RowDefinition Height="Auto"/>
                        </Grid.RowDefinitions>
                        <ScrollContentPresenter Grid.Column="1"/>
                        <ScrollBar Name="PART_VerticalScrollBar" Value="{TemplateBinding VerticalOffset}" Maximum="{TemplateBinding ScrollableHeight}" ViewportSize="{TemplateBinding ViewportHeight}" Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"/>
                        <ScrollBar Name="PART_HorizontalScrollBar" Orientation="Horizontal" Grid.Row="1" Grid.Column="1" Value="{TemplateBinding HorizontalOffset}" Maximum="{TemplateBinding ScrollableWidth}" ViewportSize="{TemplateBinding ViewportWidth}" Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

And a style for a plain button, looking like this:

<ResourceDictionary x:Class="Ellab.WPF.View.Styles.ButtonStyle" 
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" >
    <Style x:Key="DefaultButtonStyle" TargetType="{x:Type Button}">
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="Background" Value="#FF009CDD"/>
        <Setter Property="TextElement.FontSize" Value="14"/>
        <Setter Property="TextElement.FontWeight" Value="Bold"/>
        <Setter Property="TextElement.FontFamily" Value="Calibri"/>
        <Setter Property="TextElement.Foreground" Value="White"/>
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="BorderBrush" Value="#FF123F74"/>
                <Setter Property="BorderThickness" Value="2"/>
            </Trigger>
            <Trigger Property="IsMouseOver" Value="False">
                <Setter Property="BorderThickness" Value="0"/>
            </Trigger>
            <Trigger Property="IsDefault" Value="True">
                <Setter Property="BorderBrush" Value="#FF123F74"/>
                <Setter Property="BorderThickness" Value="2"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>

As always, feel free to comment, or ask.