A backup battery for your smartphone is useless without the necessary cables. So Mophie has built both a USB and a microUSB cable into its Juice Pack Reserve Micro allowing you to charge a myriad of portable devices—as long as they're not from Apple.
A multi-color LED lets you know when the Juice Pack is alive and well, or when its 1,000 mAh battery is in need of recharging itself. And while 'micro' might not be the most accurate description of its form factor, there's nothing stopping you from strapping this to your keychain if you don't mind a bit of pocket bulk. The $40 price tag is reasonable too, considering the battery pack has the miraculous power to raise your smartphone from the dead.