Here is an interesting creation using Mindstorms NXT, a Rolling-Orbital-Bluetooth-Operating-Thing (ROBOT) as its creator calls it.
This project uses two NXT controllers: one inside the “thing” and an external one that acts as the remote control. The two controllers communicate via Bluetooth. The external controller is also uses NXT motors that are very cleverly used as joystick controllers (the NXT motors can also be used like generators).
This is a great example of how multiple NXT controllers can be put to work in tandem.