In one of the "Hands on labs" on Silverlight.net, there is a "PopTheBubble" game tutorial, that teach you how to use MouseEvents in Silverlight 2. At the end he writes that you can try implementing some new features your self.
I did that to get around Silverlight alittle more. At the moment, you can only "pop" bubbles and it counts how many you popped, that's it. You never wins or dieds, pretty boring. I have plans to implement a small game logic and hi-score this week, if I get time to it. The goal of the game should be to pop as many bubbles as possible within a teimframe, 30 sec. ex. After that, if you score it good enough, you will be put on a hi-score with your name.
Try it out here: http://silverlight.laumania.net/bubble/