1. Connect your iPod — Warning! if iTunes loads when you plug in your iPod, and is set to automatically sync your entire library (erasing your iPod), you MUST stop it — hit the little “X” in the upper right hand corner of the window.
2. Open your iPod — It should show up on “My Computer” as a “Mobile Device”; right click and choose “Explore”. Alternatively, go to the Control Panel, Portable Media Devices, and double-click your iPod.
3. Unhide the files — By default, Windows hides hidden files and folders (thus the name). Go to Options (in the Tools menu), and on the View tab, check “Show Hidden Files and Folders”.
4. Find the Music — The music is stored (in current iPods) in the directory “\iPod_Control\Music”. This may have a lot of odd looking stuff in it — it doesn’t matter; select everything and drag and drop them to a folder on your hard drive.
5. Configure iTunes — Go into iTunes Preferences, and under the Advanced tab, check “Keep iTunes Music Folder Organized” and “Copy files to iTunes Music Folder when adding to the library” (settings move around a bit between versions of iTunes, but these settings will be there somewhere).
6. Add Your Files — In iTunes, select File, Add Folder to Library, and select the folder where you copied the files from your iPod. Alternatively, just drag and drop this folder onto iTunes
I did it that way when I got my Ipod touch, and wanted to get all the songs off my Ipod Mini on to a computer which didn't have any of the songs on it.