Yep, a skateboard with just one wheel. Hence the name OneWheel, which is a self-balancing electric skateboard. To go forward, you lean forward. Opposite motion for stopping and backing up. As you might imagine there isn't a ton of room for batteries which means your range is about 4 to 6 miles per charge. Watch the OneWheel skateboard in action after the break.
(Hopefully these guys can actually ship a product and stay on some sort of schedule, with regular updates, unlike BoostedBoards)