The Hornet is the coolest bike I have ever seen. It looks like a single wheel that you must learn to ride, though is actually a pretty complex piece of machinery that uses gyroscopes for balance, reaches 145 mph speeds and has unbelievable accuracy.
Still, you have to wonder how it handles sudden stops. The logical thing would be throw the rider forward a few yards, but it probably has some cool way to deal with such situations. More details.
Must be really cool, though also very scary.