The USB 2.0 cable (or USB Dock, if you have a Shuffle) that comes with your iPod has two jobs:
To connect your iPod to iTunes.
To draw power from the computer to charge up the iPod's battery.
There may be times, however, when your iPod's battery is in the red and you're nowhere near your computer. You many not even be near an electrical outlet, but on the road. Then it's time to turn to other options, including:
Using an Apple iPod USB Power Adapter. This white box has a jack to plug in your iPod's USB cable (and connected iPod) into the back end. The adapter has a set of silver power prongs that flip up and plug into a regular electrical outlet. You can find the AC adapter for around $29 in iPod-friendly stores or online at http://store.apple.com.
Figure 2-1. DLO's AutoCharger for iPod
Getting a car charger that connects to the standard 12-volt power outlet found in most cars. Several companies make auto chargers for the iPod for around $20, and you can find the hardware at stores that sell iPod gear, Apple Stores (including http://store.apple.com)and specialty iPod-accessory Web shops like EverythingiCafe (http://store.everythingicafe.com).