New Trent Easypak 7000mAh Portable Triple USB Port External Battery Charger/Power Pack for Smartphones, Tablets and more (w/built-in USB cable)
I bought this as I was going to a music festival and knew my 2000mah battery wouldn't last very long. I thought I'd get something big enough for my and my wifes phone. We get roughly 3 charges. It's small enough to fit into my wifes hand bag or a fanny pack and can keep us powered for a couple of days of light useage or a day of very heavy useage.