"Don't Cut the Red Wire" is my new project. I can't take complete credit for this, though - I got the idea from a robot I saw called SPYKE (www.spykeworld.com) and mixed it a little with the new VEXplorer bot.
My goal here was to build a small bot that was fairly stable using treads. I like the pyramidal-shape of SPYKE's motor system so I duplicated for the NXT. I added my wireless camera and a small gripper on front and now I can remotely pilot this robot to pinch someone's leg. Both tread motors are independently powered, so this robot has the ability to turn. The clickety-click noise it makes on wooden floors is also nice.
With enough motors I could add arms and maybe make the camera rotate. The robot is very stable and not top heavy at all. At the highest motor power, it'll cruise fairly quickly across the room and is fun to play with.