A couple of scientists over at MIT have come up with something novel and potentially very useful: They've figured out how to harvest body heat to power electronics. Genius idea for when your iPod conks out on the train, though that's not exactly what they have in mind. Rather, they're focused on medical and safety monitors for things like heart rate, blood sugar, and air quality.Here's how it works: The body is pretty much always a different temperature from the air around it (except on a 98.6 degree day in summer, obviously). Whenever there's a temperature difference, there is energy transferred because the warmer area heats the cooler one. So these scientists have found a way to harness that energy and turn it into power.Pretty cool if it all works out. What would you want to be able to power with your body heat?