Furniture generator

You sit down. You stand up. Energy is dissipated in the furniture padding and weight load is taken on by the framework. Instead of dissipating, all that energy could be turned into electrical energy by installing a dynamo under the cushion. As you sit down, the piston under the cushion goes down and the dynamo spins up some current. Not a lot, not enough to power a house or even a computer... but every chair could have a battery and a power outlet, and if you need to plug your laptop in you could, if there was some power built up, without having to trail a cord all the way to the wall. And as efficient as LEDs are these days, the energy generated by sitting down/standing up once a day could power a reading light for hours. And it wouldn't cost any extra energy... you're sitting down anyway, and standing back up wouldn't take any more effort than normal.

Between all the chairs, couch, chairs around the kitchen table and your bed, this could generate a lot of power. It could even be connected under the floor into one large power pool that could be accessed from any chair, but that step would kind of crimp any plans to rearrange the furniture.