Two graduate students at MIT's School of Architecture and Planning are developing what they call the "Crowd Farm", which is a smart floor that would harness the energy of people walking over it and turn it into electricity.
A responsive sub-flooring system made up of blocks that depress slightly under the force of human steps would be installed beneath the station's main lobby. The slippage of the blocks against one another as people walked would generate power through the principle of the dynamo, a device that converts the energy of motion into that of an electric current.
The obvious places to put this in use would be areas with heavy foot traffic, like malls and transit stations. Or my bedroom. It's like a never ending line of ladies in there.