They're far from the only ones working on tiny, energy-harvesting generators, but a group of researchers from the University of Michigan may well be farther along than most. Unlike some similar devices, their generator is able to scavenge even the slightest bits of energy from arbitrary, non-periodic vibrations in everything from bridges to the human body. That may not add up to a huge amount of energy, but the researchers say the generators are able to scrape together enough to keep a wrist watch or a wireless sensor runnin