When it comes to keeping your gadgets charged on the go, there are few options such as external battery packs or solar chargers. The problem is solar chargers are very slow and external battery packs require recharging themselves. Perhaps the most promising way to charge a smartphone or other device when you're away from an outlet for an extended period of time is a fuel cell.
A company called Lilliputian Systems has an interesting new fuel cell that will be sold via a retailer called Brookstone this year. The smallish fuel cell charger will be able to recharge your smartphone about a dozen times before it out of power. The fuel cell has a USB port and will be sold under Brookstone's own brand. The fuel cell is said to be about the size of a thicker smartphone and is powered by cartridges filled with lighter fluid about the same size as a cigarette lighter.
Presumably, if you need more than a dozen charges, you would be able to pop in a new cartridge and keep going. The charger will work with any device that has a USB cable. This particular fuel cell uses some unique technology to allow for longer charges than earlier devices, which typically lasted about a day. The technology includes a solid oxide fuel cell membrane on a silicon wafer. The fuel cell would be able to charge an iPhone 4 somewhere between 10 and 14 times on one fuel cartridge and the cartridges will be allowed to be carried on airplanes. Pricing for the fuel cell is unknown at this time.