Silverlight Toolkit

Silverlight Toolkit is a collection of Silverlight controls, components
and utilities made available outside the normal Silverlight release
cycle. It adds new functionality quickly for designers and developers,
and provides the community an efficient way to help shape product
development by contributing ideas and bug reports. It includes full
source code, unit tests, samples and documentation for 16 new controls
covering charting, styling, layout, and user input.

Click here to go to the CodePlex site.