We have all done it, run out of battery the moment your flight takes off, having a 18 hour car ride when your ipod will only last 4 hours of video, or other unfortunate incidents. This handy little idea has made car rides, flights, and long travels much more enjoyable, by giving your ipod an extended life.
This site has a list of different ipod batteries that will help you out.
http://www.digitalmania-online.com/iPod-Battery-Backup.html
