Charge your Cell phone by walking
Time Magazine has named the Bionic Energy Harvester, a knee brace that harnesses energy from walking, as one of the Top 50 Inventions of 2008. The 3.5 lb brace works by generating power using the same technology that lets hybrid cars harvest energy from braking. One minute of walking with a single brace generates enough power for half an hour of talking time on a cell phone. The harvester is capable of generating seven watts of electricity from each leg— enough to operate 14 cell phones.
The brace, developed by researchers at