Via the Daily Mail comes a story of a recent innovative idea which employs a microchip to capture natural motion (in this case, the beating of heart valves) to generate and store electrical current.
From the story:
The scientists from the Georgia Institute of Technology made their discovery using zinc oxide nanowires which create electricity whenever they are manipulated.
In theory any body movement - even the pinch of a finger - could be used to generate power.
Of course, given that it's 2011, they mentioned that you could charge your favorite Apple device with it. Maybe implantables are the Apple crew's next frontier? iHeart, anyone?