Man, it just isn’t camping without a smartphone. Actually, we shouldn’t be sarcastic: the modern camper probably should have a smartphone backup, along with a GPS, a flashlight, and some other stuff that needs power. And how do you get power, aside from lugging batteries?
Well, you can use this FlameStower ($90). Basically, it can convert heat into power, which you can use to charge any device that uses a USB. How? Magic. Or something.