This is for people using the USB pass through, but dont want too or cant hook it to a computer!
The Portable USB Power Supply allows you to take some USB power with you when you travel around. It plugs into any wall outlet and can simultaneously charge up to two USB devices, but it also charges its own built-in batteries. Then when you take it with you, you'll have a nice supply of USB power available to re-charge your gadget that has "suddenly" died.
http://www.thinkgeek.com/gadgets/travelpower/b4b6/