The first contest is the Silverlight Control Builder Contest put on by a few people you might know Page Brooks and Silverlight Cream's David Campbell. Custom controls submitted will be judged on their usefulness, creativity, experience and how easy they are to template.
And the big bonus is that all controls submitted will be made available as open source and free to reuse.
For a jumpstart on creating your own awesome controls, I've posted the code for a simple HelloWorld custom control that demonstrates the basic architecture.
Sans fancy logo, there is also a Silverlight Article Competition going on where the prize is a e-book copy of the new Silverlight 2 in Action book. So basically, if you write one worthy article on Silverlight 2, you will get a return of 12 chapters of Silverlight 2 goodness.
Good luck to all those who enter in either contest!