Not exactly light, but oh-so-geeky-cool:
Scientists at the University of Pennsylvania have developed a backpack that can actually generate electricity as its wearer walks. The suspended-load backpack can generate about seven watts of power solely via the motion of the person carrying it, which is achieved by detaching the pack’s frame from the load it carries and harnessing the energy generated as the load moves up and down on vertical springs. The actual energy generated depends on the weight of the load and how fast the person walks, but is usually enough to charge several handheld devices at the same time.
Perfect for that iPod, digital camera and coffee bean grinder you always take along.
A backpack that generates power [Engadget]



