Urban survivors, check this out. A tiny little 220 mAH battery for providing a little bit of last-minute juice to a dead cell phone, that also happens to look like a Jerry Can. 220 mAH is far from a full charge, but is enough to give most phones added talk time, GPS, etc. in a pinch. Certainly lots of bigger backup batteries on the market, but I have not seen anything this small.
Visit the Kickstarter page for details. First gen version will not work for iDevices.
TEOTWAWKI Blog / Alexander Wolf