ON THE GO: Inventor Dean Kamen, above, demonstrates his Segway Human Transporter, a one-person,

ON THE GO: Inventor Dean Kamen, above, demonstrates his Segway Human Transporter, a one-person, battery-powered scooter, in New York. He thinks the scooter, which travels at a top speed of about 17 miles per hour, will replace cars in big cities. Other demonstrators, right, show how the scooter uses gyroscopes to keep it upright and discern where the rider wants to go.