Lego Mindstorms is pretty cool, yep, and I've heard a lot about Karel.  We have put together a wrapper for KPL which allows KPL-easy programming of Lego Mindstorms - wrapping their API like we did the DirectX api, to make them easier to use.  We haven't released it yet, but we may get to that next what with KPL v 2 now going out the door.  Another reason we've hesitated on that one is that we thought we might be better off doing the same thing with the new Lego Mindstorms NXT robots.  Does anyone have feedback or experience with NXT yet?