Open iTunes and select edit/preferences/advanced/general. Put a check mark in the box marked "copy files to iTunes music folder when adding to library" and also "keep iTunes music folder organized", then click 'ok'.
Connect the iPod whilst holding down the shift/ctrl keys to prevent any auto sync, and if you see the dialogue window asking if you want to sync to this itunes library, click <b>'no'.</b>
Then go to file/add folder, open 'my computer', select your iPod and click 'ok'.
The music files should transfer to your iTunes.
If this doesn't work (and it may not because officially it's not supposed to), there's Yamipod
http://www.yamipod.com/main/modules/home/ This is a free program that transfers music and playlists etc from iPod back to the computer. However, it does not transfer playcounts/ratings etc.