You need. Senuti. It's Itunes spelled backwards. It's a free app and it works great. Download and install it.
Plug in your ipod.
iTunes might launch automatically, but you just ignore the request to sync to library and all that. Instead launch Senuti, define the folder you want to upload to, and upload your ipod library to to it. Then take all the songs and drag them into your iTunes library.
Once they are in your library delete the files out of your Senuti folder.
Here's the link where you can download it.
http://www.fadingred.org/senuti/