Backpack electrifies your hike

Go for a power walk—literally—with a backpack that gets energy from the bouncing made while you strut. This invention can generate up to 7.4 watts, enough to charge "a cell phone, an MP3 player, a handheld computer, night-vision goggles, and a water purifier" all at once, says National Geographic. Look how happy he is! Many bloggers are in love.

Unlike its solar-powered cousins, this backpack can rev up your gizmos even if you're just trekking to the Chicago "el" in gray February. Whenever it hits the market, they'll have to come up with a less clunky name than "suspended-load backpack," but hopefully one with less unfortunate rhyming potential than the yellow Juice Bag (right) which you can buy for $200. The $230 Voltaic backpack led the pack when it hit the scene last fall. You can also shop for the Reactor backpack or Solar Flare messenger bag. The iPod-friendly O'Neill H2 solar backpack hasn't hit the States yet.