Swedish Designer Eddi Törnberg has designed the best human-powered work station we've seen yet because unlike other concepts that require you to do things like ride a bike while you're working, it doesn't require a person to do anything more than sit and work. The project, called "Unplugged," powers the various gadgets we use to work -- laptops, lamps, etc --through our small constant movements and body heat.
The desk chair is equipped with a metal seat that gets hot as a person emits body heat, but the underside stays cools through a pattern of metal fins. Electricity is produced through the Seebeck Effect where an electric charge is created when a material is hot or warm on one side, but cool on the other.
The other energy-harvesting part of this set up is a rug that lies under the desk that is outfitted with piezoelectric crystals that generate electricity when pressure is applied to them. Each random shuffle, stomp, and rolling back and forth of the chair is a source of electricity.
The final part of Unplugged is plant-powered rather than human-powered. A potted plant provides electrcity through a process similar to a potato battery.
Unplugged is definitely more of a concept than a working product, but if this set-up were put to use, it could generate a nice chunk, though probably not all, of the energy needed to get through the workday.