The Energizer XPal is the best I ever wooted. 8000 mAh Li-Po battery with 3 outputs.
A USB, 9-12v & a 16-19v for Laptops.Charges my Galaxy 2 about and as an example,
I have a 12v battery operated fan that will run on 8 "D" batteries for 24 hours, and will
do the same fan for about 16 hours. Gives my netbook at least 3 hours. I carry a Duracell 2oz 18mAh. That will charge inline to charging my phone.