Anker 2nd Gen Astro 6400

For the size and weight of an energy bar (and the cost of a box of them), you get 6,400 mAh (enough for four iPhone 4 charges).
2nd Gen Astro 6400
Price $26.00

Specs

Screen Size (diagonal) 0.25

 

Weight 5 oz

For the size and weight of an energy bar (and the cost of a box of them), you get 6,400 mAh (enough for four iPhone 4 charges). Bonus: A circular LED display shows the unit’s remaining battery life in 10 percent increments.