Stitchway UltraPower portable backup iPhone battery charger:
I bought this on Amazon.com for a mere $6 (click on picture above to take you to the product page).
How it works: It’s this compact little square gadget that is probably smaller than the palm of your hand that offers you the option of a wire-free recharge for your phone, or iPod on the go. I’m always on my phone, checking Facebook, using foursquare, playing temple run, or texting, so half way through the day my battery levels are quite meek – which sucks if I’m out of the office or not at home.
This is a life saver. You have to charge it in advance using your regular phone/ipod charger, and just slip it in your bag or your pocket. Whenever you need it later, you connect it to your phone and it’ll charge it up – No wires, no fuss. It can charge my iphone right in my handbag as I go about my day.
I measured the time it takes to charge. On my phone, from DEAD to 79% it took about 2 hours. A must have.