We are using Dagu's tracked chassis. The body of the vehicle is 3D printed. The BeagleBoard-xM is used as on-board computer to control wide range of sensors (such as ultrasonic range finders, compass, cameras, etc.).
Thanks for the informative response regarding the analog cameras, sounds like you have done your homework when it comes to spec'ing out your robot. I was thinking about picking up some cheap USB webcams for my robot SPANR but now I think I'll need to investigate further (lens viewing angle being an important factor in robot vision I expect).
I've yet to fully experiment with different surfaces but I have had it running on the rug in the video (tough, rough surface), thick carpet, an uneven polished concrete floor and astroturf (fake grass, plastic bristles). The robot strafes (runs sideways) on all surfaces with some wobble/change in orientation which is sometimes random and other times it can be anticipated (centre of gravity affects it, as does unevenness of the surface). As has been suggested in the comments on my robot page I may need to implement feedback from gyro/accelerometer/compass etc which I hope to look into. One major problem with the wheels is that I cannot turn on the spot (tank driving where I drive the left wheels forward and right wheels backwards together) as the O-rings which provide grip will pop off their wheels due to the slippage required on the wheels and the direction of travel/friction is perpendicular to the small wheels (this doesn't happen on all the wheels but it's often/regular enough that I'll need to stop and fix the wheels after attempting a turn).
Thank you very much for the information about wheel performance! I am currently thinking about different alternatives for trucks (different types of wheels) and your experience is a great help in decision-making process.
As announced here in comments and on the blog, we are working on the wheeled version of our "Shark" robot. Today we have made the first test driver. Please check out the new blog post for some more details and pictures.