Callpod's Fueltank Uno ($39.95) is a small rechargeable battery that allows users to charge their smartphone, including iPhone, 3-5 times off of one charge of its rechargeable lithium-ion battery. It uses device-specific adapters covering more than 3,000 different products from all major manufacturers; in addition to Apple, there's RIM Blackberry, Motorola, Samsung, LG, Sony, Jawbone, Plantronics, Nokia and others. See here to learn more about the Fulltank Uno, whch weighs 3.5 ounces.