What can you say about Joe Nagata? Simply a LEGO Mindstorm genius
His very interesting assortment of creations can be found at...
Joe's Mindstorms Gallery
** GO THROUGH THE LIST. THE WHOLE LIST. YOU WON'T BE SORRY **
Here are a few of my favorites.
Balancer A1 [k080]
Turing Machine [k025]
Wonder how he does it? You can find build instructions to several of his creations in his book: Joe Nagata's Lego Mindstorms Idea Book