GE Solar Formerly AstroPower, The largest US solar company.
BP Solar The Solar arm of British Petroleum, a genuinely forward-thinking oil company, that not only "gets it", is actively working towards hydrogen/solar as fuel sources, and away for oil.
Fuel cells produce electricity from hydrogen, with no moving parts and no pollution. Several car manufacturers expect to have fuel cells cars within three years. This technology is going mainstream fast...
Manufacturers. All of whom have serious deep-pocket investors, like Ford, Intel, DaimlerChrysler, Texaco, GE.
Ballard Power Has an excellent Java animation of how fuel cells work.
Two main uses. The first use is in cell phone relays - fewer drop outs, stronger signals. The second use is cabling that allows electricity to flow with no resistance.