I've seen several questions related to timers on forums and in internal mail so I thought I'd toss up a simple example. To create a timer, you have to use the DispatcherTimer in the System.Windows.Threading namespace.
Here's an example of a simple counter that uses DispatcherTimer: Run this sample.
And below is the code:
Before Silverlight 2 (with Silverlight 1.0) you could create an animation using a Storyboard, however, Storyboards are for animations so this was a hack. Also, I believe the DispatcherTimer route offers better performance. Still, if you are using Silverlight 1.0 or have some reason for wanting to use a Storyboard to simulate a timer, see How to: Create a Timer in the Silverlight 1.0 documentation.
Sam Landstrom - MSFT