We worked Saturday to get the omni-directional drivetrain setup and it works great! It's just mounted on some plywood, but does a good job. We used Dr. Joe's instructions for using Dewalt transmissiona nd AndyMark omni-wheels. This was before we wrote the code for driving it (it's just using the stock two channel mixing), but it now drives using two joysticks. The control setup is very similar to Halo with the left joystick controlling forward, back, strafe left, and strafe right, and the right joystick controls rotation. This is just a video of us seeing how fast we can get the bot spinning when we first got it running.
http://www.sartanyac1541.com/videos/RobotSpin.mpg