Robert Ingebretsen (WPF program manager) has released a version of his Simple Styles for the Feb CTP of WPF. The styles provide great examples of how to alter the appearance of the common WPF controls including
- Button
- CheckBox
- ComboBox
- Expander
- GroupBox
- Label
- ListBox
- ListView
- Menu
- ProgressBar
- RadioButton
- ScrollBar
- Slider
- Tab
- TextBox
- Tooltip
- TreeView
The styles are well-factored into a single Xaml file for each control type. If you're looking at writing custom styles for any of the built-in controls, or just want some simple and attractive styles to use in your application you should definitely use these as a starting point.