YamiPod is a totally free application that allows you to manage your audio files in your iPod. Using YamiPod, you can order and create your own library with your music files.
YamiPod allows you to import lyrics by searching the web, to transfer the audio files from your iPod to iTunes, it is really well organized and it is very easy to use.
In addition it can be launched right from your iPod, so it doesn't matter if it is not your computer where you want to run it, you can do it.
If you have an iPod and you need a manager, this is what you are looking for.
It also supports the new iPod nano.