for cellphones...

http://www.herringtoncatalog.com/es328.html

Finish Critical Calls — Get Hours of Back-Up Power From a Single AA!

Just throw a Pocket Power in your jacket, and you’ll never be stranded by a dead cell phone battery. Using any alkaline, lithium or rechargeable AA, Pocket Power weighs next-to-nothing — thanks to rugged but lightweight aluminum construction.

Too bad they dont mention much about the connectors and which phones are compatible.