If you are looking for some nice controls for your next Silverlight 3 application, then make sure and stop by VectorLight.Net.  These controls seem to be very light weight and stable, and best of all, they are currently free.  A Live Demo of the controls can be found here.

The list of current offerings include:

• Color Selector
• Dropdown
• Fieldset
• File upload
• ItemViewer
• Magnifier
• Main Menu
• Menu ( popup )
• Popup Bubble
• Popup Dialog
• Popup MessageBox
• Progress Bar
• Rich TextBlock
• Rich TextBox
• Roller Blind
• Scroller
• Spell Checker
• Table
• TextBlock Plus
• Text Rotator Blind
• Tree View
• Viewer