Dave Astolfo has released a few teaser pictures of a shape-shifting tankbot built around the NXT and using the new treads from the new LEGO Technic Snowmobile. Take a look here:
Shape-shifting tank on NXTasy
It sounds like he'll release some more information on it soon, which would be great. I've used these treads some already, and I'm lookin g forward to a couple other neat uses I've thought of recently.