This is way cool — Toyota premiered its i-swing yesterday at the Tokyo Motor Show. The concept can be used in two-wheel mode for busy sidewalk travel, or three-wheel mode for an experience not unlike a street luge, I would imagine. Except that running feet-first into the delivery truck you didn't see until the last second would probably be much less pleasant than simply grazing the track wall, but I digress.
The vehicle is controlled by a joystick and "ski-like" movements made by the driver, and it's apparently enhanced by artificial intelligence "to grow, learning the habits and preferences of users." Scary. Head on over to engadget to learn more.