A recent article by Popsci.com brings up a new, alternative energy idea that hasn't been discussed in the same ways as solar, wind and hydrogen.  That is power harvested by humans.  Now, before "soylent green is people" runs through your head, I mean kinetic energy.

Human beings create new energy in large amounts, mostly stored in our body fat, but also in our muscles.  That energy is used and burned in our movements, which is called kinetic energy.  By harvesting kinetic energy from simple actions like walking or running, you could be recharging more than just your body.

Human energy won't get you off the grid, but it will help to make a small difference.  Green Microgym, in Portland, Oregon, has created a stationary bike that will harvest the energy you put out during your workout.  Riding the stationary bike turns a generator, which then helps to power the building.  As the machines are fine-tuned, the amount of energy produced and stored in the generator could increase.

There's also dance floors in the Netherlands that use the same kinetic energy.  The company, called the Sustainable Dance Club, utilizes the piezoelectric effect, where certain materials create an electrical current when they are bent or compressed.  As the people in the club dance on the floor, it is compressed by half an inch, and makes contact with the piezoelectric material that is underneath.  In the future, this floor could power more than the LED lights in the club, and eventually power the whole club itself.