The farther you travel from civilization, the more impractical your USB-rechargeable gadgets become. If your iPod runs out of juice while you're backpacking through Borneo, suddenly that high-end MP3 player is just dead weight.
You may not be able to find an iPod charging dock in the Arctic Tundra or the Australian Outback, but your chances of finding a local general store stocking AAA batteries are considerably better. The real trick is finding a decent MP3 player these days that will take AAA batteries. Don't worry, we've got you covered.