Here is an article [with video] that I found about a small robot for ‘rough’ terrain. The article says the basic unit can be either tracked or wheeled, but the video shows only the tracked version. From context this appears to be strictly remote controlled, with no onboard navigation or sensor interpretation. Something like this would make a good base [just add smarts ] for the cross-country / Darpa style challenge idea that has been bounced around at WCRS events on a regular basis.
The press release linked from the article has a ‘little’ more detail. There is also a facebook page with more pictures, still only the tracked version though