Innergie PocketCell

The 2.5-ounce PocketCell earns our highest praise, thanks to a smartly designed cable that holds mini- and micro-USB connectors (for most portable electronics), as well as Apple's proprietary 30-pin one. This lets you charge any device, without having to stow spare cables. Though it has the small­est battery, it still supplied more than half the juice to a Kindle Fire (and can also do an iPad halfway on a full charge). We also used it to revive a dead iPhone to full charge and an Android phone to full charge (without having to plug it in again). [$80; amazon.com]