So here's what I've done with the BigTrak so far. I've mounted the IGEP on the back, mbed in the nose and arranged battery power for all the electronics and set up WiFi to remote control it. Boring technical details are at http://www.srimech.com/projects/bigtrak/. The audio on the video is poor, sorry about that. I wanted to be able to hear the motors and my voice is pretty soft at the best of times.
Annoyingly, the biggest challenge by far has been getting the drivers working on the IGEP. It's a neat board, but not very popular so there isn't much community support out there for it. It took me a couple of weeks to get WiFi and usb-acm (necessary to talk to the mbed) working at the same time, and the next challenge is to get it to recognise a USB webcam.