So my senior design project was a drive-by-wire ATV with a semi-autonomous mode built in. We used an Innovation FIRST MiniRC (also known as the 2004 Edu RC) with a Garmin 18-5hz GPS receiver. The receiver pipes data out to the MiniRC via the TTL port. We attached a 900Mhz serial radio modem out of the "program" RS-232 port on the MiniRC to transmit data back to a laptop. The laptop has a map of the area that can be clicked on and the ATV would drive to the location. I'm not saying it is the best it could be, but you can check out what we did on our website at
http://mem15.no-ip.org . Click on the Documents link on the left and you will be able to find (in one form or another) all of our documentation and how to recreate it.