Voltaic Systems offers up 4 watts of power at full charge. One hour in the sun generates 3 hours of iPod play time or 1.5 hours of cell phone talk time. Want to use the backpack charger at night? No problem. The backpack also comes with a removable battery back either stores excess energy from the sun or charge via USB cable. The Voltaic Backpack retails for $249.
HYmini charger is your own personal wind turbine -- just hook it up to your camera, cell phone, or iPod while you're walking through the wind and watch the charger go. A 6 watt rechargeable powerbank stores excess energy for later. For days when there isn't any wind, hook up the HYmini to solar panels or an electrical outlet. The HYmini Deluxe retails for $75.
BoGo Light, a powerful solar-powered flashlight that lasts 20 years and can shine for 5 hours at a time. There are plenty of other solar-powered flashlights on the market, but the BoGo Light comes with a feel-good bonus: for every flashlight that you buy, one goes to people in developing countries that lack reliable access to electricity. The BoGo costs $59.99.
backpack hydroelectric generator from Bourne Energy may solicit some strange looks while you're lugging it down the street, but the three foot-long, 30 pound prototype device is nothing if not useful. A single self-contained unit can generate 500 watts of power from any stream of water. When combined, multiple backpack units can generate up to 30 kW. No word on a potential release date for the $3,000 generator, but the military is supposedly interested.
LightCap 300, a combination BPA-free one-liter water bottle, solar-powered lantern, and waterproof container. The bottle features 4 ultra-bright LEDs along with a red LED nightlight. At just $29.95, this multipurpose device is definitely worth shelling out for.
Presso, a manually-operated espresso maker that combines hot water from a kettle, finely ground coffee, and mechanical leverage to produce a quality cup of espresso. The Presso retails for $150 in the U.S.
Freeplay Companion is a great option. It's a radio and flashlight all in one, meaning that you get two valuable tools. Plus it has the option to use solar if you're feeling lazy. The Freeplay Companion retails for $32.