New Trent Easypak 7000mAh Portable Triple USB Port External Battery Charger/Power Pack for Smartphones, Tablets and more (w/built-in USB cable)
I used to have a little pocket charger that used 2 AA batteries and a host of connectors which I kept in an Altoids tin.  This Trent charger is amazing.  It charges two phones at a time.  I find that most of the time my daughter totes it around, so I guess I'll have to order another one.  This is a great gift for people on the go.  I haven't tested it to capacity, but I do know that it is good for at least 3 charge-ups.