I was in my local Radio Shack picking up some AA batteries today and noticed they had a Parralax BASIC stamp kit for $99. I think I will have to go back and get one. I want to use it with a couple of photo diodes to start/stop a timer function at a set distance along the track and calculate/display scale speed. Perhaps also add code to count axles and randomly do defect detection! I don't know what other projects I could come up with, but I'm sure there are more out there...