The German "ZipCar"

In the U.S. there is a company called ZipCar which sells hourly car rentals. They have rental cars parked at various places throughout Boston, and if you want to rent the car for a few hours, you just go and pick one up, and then return it later on.

In Cologne, DeutscheBonn has a similar business model, but with bikes. These bikes are just parked throughout the city, and they have a phone number on the bike for you to call and rent the bike.

After you call, they send a signal to the bike that unlocks the pedals. Pretty nifty.