In german cities there has been a system called "Call a Bike", driven by the german railway "DB".

These bikes were standing all over the town, you could take one and rent it by sending a SMS. When finished your ride you sended another sms and leave the bike where you have been, ready to use for the next renter.
Payment was done via the mobile phone provider.

This concept was perfect for shorter rides, e.g. from the metro to your home. Just leave the bike in front of your house, and forget about it. Next time, go a few meters and find another one to rent for your ride into the inner city.

Starting this year, they now want the bikes exclusively at certain, reserved places. Since then I never used one, because these stations are too far from my home. Maybe tourists have interesst in such a system, but its practical use on a normal workday is very limited.