There something appealing about RC cars to people of all ages. Maybe it's the closest you get as a kid to driving a real car, and when you get a car, you can do what you can't on the street.
Blair Kelly has created the Wifly Mini - the ultimate Arduino powered RC car. In essence, it's a modified Mini Cooper remote control car that you control using a games console's joypad (or steering wheel controller) over Wi-Fi. A mounted camera let's you see the world out of the eyes of the 'driver', and force feedback support really puts you in the seat.
This is a pretty cool project, and you can read more on Blair Kelly's page, which gives a run-down on all the components and how it was built.