I don't think there is any type of system in place for charging from one device to another yet. I've read that they're working on ways to connect devices through wifi without even being on a wifi network at all, but I lost track of how far along they are with that. If you have another device with NFC you should be able to use Android Beam if you have Ice Cream sandwich on both devices or you can use Doubletwist to move files through NFC.