A couple of years ago (ok, eight years or so), I went to my local toy store and bought the Lego Mindstorms Robotics Invention kit for my kids (they were only three years old at the moment, but the guy behind the counter didn’t know :-). I built quite a few robots, among them were roverbots using infrared lights for prozimity detection and even a dragracer that changes gears when it reached a certain speed. It was fun!
I’ve been waiting for the next version of the Mindstorms kits, and really enjoyed an article I read at the MSDN Coding for Fun site about a .Net SDK for communicating with the RCX. I found the link over at Scott Guthries blog.