Just found this great and so complete list of Silverlight controls enlisted by Tim Heuer at his blog.
He says
:
I figured it would be a good idea to do a larger dump of those that I’m aware of (and hope you add comments to point me to others so I can amend this list) and help make you aware of them as well. There are a ton of great resources out there for Silverlight developers and I’m always impressed how our developer partners are extending our platforms to make tools for developers (and most of the time better than we do :-)).
Here’s his round-up of controls (alphabetically – links here will jump to their section):