Here is a neat idea. The electric Yike Bike folds into a two foot by two foot space. (It takes 20 seconds or more to fold it.) It travels up to 6 miles at a maximum speed of 12 miles per hour and will cost 3,900 euros ($5700 USD) when in goes on sale in mid 2010. It can carry up to 220 pounds.
It won't be sold initially in the USA.
Here's a link to the YIKE BIKE YouTube Channel.