Engineering students at Rice University have detected a leak in the system of human energy use: the force we waste on the impact of each footstep.
So they've created a pair of shoes that will harvest the energy of the heel strike with little effect on the stride of the wearer. (Researchers at USC developed a similar concept a few years ago that involves piezoelectric crystals, but we've yet to see it in use.)
They're not stylish, but they work. The students recommend that whichever enterprising inventor follows in their footsteps focuses on making the device smaller and lighter.
HT: Laughing Squid.