Who needs USB battery packs? This is better....
The PowerWalk system looks like an athletic knee brace and weighs about 1.7 pounds. The braces generate about 12 watts of electricity when the user walks at a normal pace; an hour's walk can apparently produce enough juice to recharge four cell phones.
iPod Touch 5G 32GB, Touch 4G 32GB, Clip Sport 8GB. Rockbox-> Clip Zip 4GB, iPod Nano 2G 4GB, iPod 5.5G 80GB
2012 Nexus 7 32GB, Asus MeMoPad 8 16+64GB, LG Optimus G Pro, Nokia Lumia 900 and Lumia 520