I just use an external battery pack, the predecessor to this one:

http://www.amazon.com/GearPower-Port...8592231&sr=8-2

Instead of charging off a computer, I usually use a little AC USB charger, like this:

http://www.dealextreme.com/details.dx/sku.19242

Works great. Simple. Small to carry. On airplane trips, I leave the external battery connected; I don't know if that's more efficient or not.

Have a good trip!