I made an Arduino based robot using an old RC car.
A laptop reads in data from an Xbox360 controller. The laptop transmits commands wirelessly to the Arduino via bluetooth.
The best part about the project is the camera which can pan and tilt. It transmits a video signal back to the laptop.
Here is a video which demonstrates the functions of the car. http://www.youtube.com/watch?v=BstbG4UrVfQ
Here is a blog I setup which has a parts list on it. http://creeperbot.blogspot.com/