Telerik an awards-winning producer of ASP.NET Controls has made the demos of their Silverlight controls available online.
The actual controls are not released yet, but in the demos you can view
the related XAML and C# markup. The demos feature the following
controls: RadAnimations, RadButtons (6 types), RadCombobox, RadListBox,
RadMenu, RadProgressBar, RadSlider, RadTabStrip, RadTextBox,
RadTreeView and RadUpload.
More details from Todd Anglin's blog post.