I covered the iGo Charge Anywhere last month (see previous post) -- a convenient and lightweight portable charger with two USB connectors. Plug it in to an outlet to charge up the internal battery, and then bring it along to charge your various devices using their various USB power cables.
But if you're on an extended trip, and may not be able to plug in to a wall outlet for a while to charge up again, then check out the iGo powerXtender. This is a portable charger that uses two standard AA batteries, you can always reload on the go. iGo says it provides up to 10 hours of talk time on phones, 20 hours of play on gaming devices, or 28 hours of listening on media players, with premium batteries.
However, the powerXtender does not have USB outlets. Instead it uses the iGo interchangeable power tips, which can be purchased separately for a huge variety of devices, including mobile phones, smartphones/PDAs, MP3 players, Bluetooth headsets, digital cameras, portable gaming devices, and GPS systems.
The iGo powerXtender is around $15, and includes one free tip that you can order online.
See my Portable Power Accessories Gallery for more on portable chargers
Find the iGo powerXtender on Amazon.com