Here's a guest blog post by robot builder lama-mantis who has produced a series of robots on treads. That's what he says about them:
"There are a lot of critical situations where humans can't help. A nuclear disaster is too radioactive, a bomb is to risky, a fire is too heat, etc. But there's still help needed. And when humans can't help, robots do it. They aren't organic, so they can survive high radioactivity. They don't have a life, so it doesn't matter when they explode. They can be made of material that can survive high temperatures, so that they can't melt.
I, Lama-mantis, built a serie of robot called 'Complix'. They are made for critical situations. My Complix robots are made with the NXT hardware, and the structure is built of TECHNIC pieces. They have treads so that the robots can move over heavy terrain. You can check them out here:
Robot profiles: http://www.us.lego.com/en-us/mindstorms/community/profile?builder=lama-mantis
Some videos: http://www.youtube.com/playlist?list=PL8dXxY9Z0w9OSH-k02aXR_j953yh1E6vN
Of course, they don't survive big explosions and the plastic will melt in fire. But the Complix robots can inspire other robot engineers to make robots. Maybe a Complix-like robot will save your life in the future!
I hope you like it!"