A battery powered Raspberry Pi set atop a LEGO Mindstorm NXT robot. The Raspberry Pi is controlling the robot using nxt-python. Commands are sent to the Raspberry Pi through the wireless keyboard - read using a small Python script - allowing the movement of the robot to be controlled.
It was really easy to set up, except for the stupid 5m USB cable connecting the Raspberry Pi to the NXT brick. This took some balancing.