Whether or not for practical reasons (checking the weather forecast, for instance), many campers insist on staying plugged in while getting in tune with Mother Nature. For that reason, solar chargers have become more or less standard issue. But the utility of these devices actually extends well beyond the trail. If you're always on the go, the FatCat Solstice II can mean the difference between getting things done and running out of juice. Available on Amazon; $100.