A-Bike

This is the awesome A-Bike from England.  It only weighs 13 lbs!  It can accommodate people up to 6'3 and 85kg, and it all folds down to an itty bitty package you can carry around in less than 10 seconds (that's with A LOT of practice).  I've heard more like 20 seconds.  Anyhow, the wheels are tiny, but with every pedal you make the wheels actually make three revolutions.  The engineering is great - all the chains and gear are inside the frame so you don't get your hands greasy with all that oil, and it's water resistant.  Check out the official A-Bike Website for videos and more info.  I've been waiting for the price to drop since it's introduction in 2004, which it has, but it still costs 150 pounds right now ($300 US).