nextbike is a novel approach to bike renting in a big city. Bikes are available 24/7 and start at 1€/30min or 9€/24 hours. nextbike makes it easy to rent a bike - all you do is download an app (iPhone/Android) and use your location to rent up to four bikes at the nearest terminal. Not an app fan? Rent at one of the terminals or call ahead and rent over the phone.
If you're traveling from one destination to another, you can rent a bike at one station and return it at another official location.