Mophie Juice Pack Reserve Micro
If there's one near-universal flaw of smartphones, it's that they always seem to run out of juice too soon. That's where Mophie's Juice Pack Reserve Micro comes into play. The keychain-sized device is like a spare gas can for your gadgets: It packs a 1000mAh battery and integrated micro-USB cable. When your phone's battery runs low, just plug in the Juice Pack and top off its charge.
As a bonus, you'll look like a super-geeky version of James Bond when you connect it.
Available for $39.95 from Mophie.