Power-Over-Ethernet could end up being a universal powersupply for much computer hardware as the cables and connectors for it are the same all over the world.
Perfect for slipping into a laptop bag or pocket, all of Iomega's 2.5-inch portable hard drives are host powered, requiring no external powersupply beyond the power provided through the USB bus on a personal computer, laptop or netbook.
This computer has no internal powersupply, but when a specially designed reader sends out a radio signal, a tiny antenna draws power from the wave and uses it to wake the computer up.