When I was preparing for RIAPalooza, I created and blogged about Creating a Simple Silverlight Countdown Blog badge.
It was great but I wanted to updated it for the next event and realized that recompiling it was not really a user friendly option. The answer is that I updated the widget to have a level of parameterization so that I could easily update it without having to recode everything.
My write up and source code are at - Updating the Simple Silverlight Countdown Blog badge