What would you do if your computer crashed and all of your music was stored in iTunes? What if you didn't back it up the way you are supposed to? The songs are all on your iPod, but what good does that do you?
You need Pod to PC. This is one of the simplest, most useful programs I have ever seen. You turn on your computer, boot iTunes, and plug in your iPod. Then you run Pod to PC. It examines your iPod, examines iTunes, and then determines which songs on the iPod are not in iTunes. And with one click, it transfers them. Just like that. With content info and your playlists. As if you had backed them up.
$10. Well spent. (Note - there is even a free version for the Mac!)