Bike share system that gives energy to the city.

Like, actually feeds back energy to the grid (in addition to the revitalization aspect of it all!)

http://www.engadget.com/2009/07/16/hybrid2-public-bike-concept-promises-to-help-power-city-buses/

... the hybrid part of the bike (a regenerative braking system) wouldn't be used to help power the bike itself at all, but would instead store the energy in an ultracapacitor that'd then feed the energy back into the grid when its parked at a special bike stand, which would in turn be used to help charge the hybrid electric buses. Not one to overlook an ingenious little detail, Chen has also devised a special card RFID card that would not only be used to unlock the bike, but keep track of the energy that each rider generates -- build up enough credits and you can ride the bus for free.