Darth Vader's NXT Apprentice: Droid Tank

This is way cool - check it out!
http://thenxtstep.blogspot.com/2008/07/clone-wars-new-star-wars-film-coming.html

The design is pretty well written. You can find it by following the link or directly here: http://mindstorms.lego.com/nxtlog/ProjectDisplay.aspx?id=8651cdc3-737f-47bd-bbd3-34c3b13731cd