I'll try not to get too technical here, but this just too crazy not to share!  Two guys from the University of Wisconsin are working on technology called "reverse electrowetting", which harnesses the energy produced from the motion of a shoe landing on the ground.  This energy is usually just lost as heat. Apparently humans create a lot of energy as a kilowatt of power can be produced through sprinting. The reason this is interesting to us is that the energy can then be used to power just about anything! Your cellphone, ipod, laptop, etc.  

Shoes could be built with USB ports, so any device could be charged from them from the energy gathered while walking! It's possible the energy gathered would be enough to store and operate a wifi hotspot right in your shoe!  How crazy (and awsome) is that?!