DIY battery-powered USB charger
Build you own USB phone recharger: (dubbed the MintyBoost).
This is probably one of the most detailed projects I’ve seen on Instructables (and is a major upgrade from the previously-mentionedportable USB charger). At first glance the level of detail seems a little daunting, but in the end it sounds like something that even the beginner with enough motivation could tackle. The charger can give 1 full recharge to an iPod video, 5 recharges to the shuffle, and 1.5 recharges for the mini – which, if you use rechargeable AA batteries, is a pretty good deal.