I recently had an article published that shows how to build a Windows Forms application using an accelerometer to measure the performance of a vehicle. By using basic physics equations, a vehicle’s current speed, distance traveled, horsepower, and other performance metrics can be derived from the acceleration values provided by the accelerometer. It's pretty cool, check it out.
http://blogs.msdn.com/coding4fun/archive/2007/02/18/1709215.aspx
http://channel9.msdn.com/ShowPost.aspx?PostID=283953