I feel like I missed something obvious. Maybe you already knew this.
Remember the Segway scooter created by Dean Kamen and announced in December? Battery-powered, using computers and gyroscopes to make it almost impossible to tip over. Kamen has a wheelchair going through final FDA tests that uses some of the same technology to make it impossibly stable.
Did you realize the Segway scooter only has two wheels – next to each other? I pictured a traditional scooter, with a platform behind the handle. Nope, two wheels on either side of the handle, with just enough space for your feet. It’s little! Nonetheless, the technology in it makes it difficult to fall over or knock down, and somewhere there’s enough batteries to push it eleven miles, at speeds up to 12.5 mph. Hey, I’m impressed.
There’s a clear photo and diagram with this article about Kamen winning a $500,000 prize for inventors.