Boards
These scooters with two front wheels
http://carscoop.blogspot.com/2006/05/piaggio-mp3-three-wheeler-scooter-with.html
That claims they're more steady but they don't look it. In fact if I were the sort of person who was a bit worried about the two-wheeled nature of a conventional scooter I'd guess I'm probably not the sort of person who should be riding any such device around. It still looks like it'll fall over pretty easily.
In short: they look a bit pussy, right?