I got a Just Mobile Gum Pro about 3 years ago and love it. It's great for charging my smartphone, Kindle or e-cigarettes on the go.I bought a portable charger to carry with me. It's literally the size of a lipstick tube.
http://stores.halo2cloud.com/-strse-17/Halo-Pocket-Power-2800/Detail.bok
It is only good for small things like iPODs and phones. And I find that it doesn't give 100% charge before it is depleted, but it's good in a pinch. I charge it up and carry it around and for those times when my cell phone runs really low, I plug the phone into the charger and can get about 50% battery charge. Then when I get home I recharge the Halo.