I much prefer the look of Quirky's Trek Support backpack to Voltaic's solar-powered backpack from years ago, and if enough people agree with me and pre-order it (for $US130), they'll even put it into production.
Just like the rest of Quirky's products, the backpack design has been crowdsourced, but it just needs enough people to pre-order it before putting it on the factory line. It's about half the price of a solar-powered backpack, and doesn't have the obvious panels on the front - choosing, instead, a subtle grey and blue colour-scheme.
Various pockets have been stitched in, with the main compartment large enough for a 15-inch laptop. The rechargeable battery, housed in a lower compartment, can charge up the gadgets via USB. It might not be as planet-friendly as the solar backpacks, but at least you can ensure your iPod won't run out of juice on a winter's day. [Quirky via GearLog via SlashGear]