Just thought I'd give a heads up on the iGo PS00264-004 powerXtender that uses the AA batteries from the last woot where I picked a pair up on a lark. I know a lot of you see this and consider it but are uncertain. I will give you the low down on it here.
These little gems do work for emergency power. Thats what they are made for, like if there is a massive power outage because of hurricane. If your phone will charge on a .5 amp charger these will work. The caveat is you need to turn the phone off first. I found that with the phone on, the charging indicator on the phone was cycling off and on. Once I turned the phone off it charged steadily until the little blue power light went out. I own a Nexus 4 which has some horsepower. The set of included duracell batteries got me 24% charge. Not bad for two little AA's. With some eneloops or lithium AA's you'll get even more mileage out of them. Obviously not a main charger roll, but as SHTF with a crap load of the cheap batteries from woot scenario, I feel confident. These will keep going after your fancy 10,000mah battery charger runs out of juice. At this price I'm picking up 3 more for gifts for loved ones and more AA's next time woot puts up more cheapies.
Note: only works on devices that charge with micro-usb or old non-lightning iStuff. Dont bother for tablets. You would get like 1-5% charge if it even had enough juice to get the charging started. They do have other tips on iGo website if needed.