Although this isn't a NXT robot, it shows how limitless the possbilities are with LEGO Mindstorms. Rick just posted about a Gecko robot invented by Carnegie Melon, so I was surprised when I went on brickshelf and just happened to see a LEGO robotic gecko, made with the RIS, that can also climb walls. You can see more pictures here, and there's also a video of it crawling up a wall, here.
-Jonathan
-Jonathan