So, you've got music on your iPod that you don't have on your computer
It doesn't matter how you got in this predicament -- maybe you've lost a hard drive (or an entire computer), or you've accidently deleted just a little too much, and for one reason or another, you don't have the original source of the music.
If any of that sounds familiar, the time to fix it is now -- before you lose your iPod (and your music), or iTunes manages to get set to automatically sync your entire library (its default state, if you have to re-install it) and starts deleting all of the songs it doesn't know about.
Unfortunately, the standard tool for transferring music between your iPod and your computer (iTunes) is one-way -- it'll put music (or videos, etc.) onto your iPod, but it won't retrieve it back. Why Uncle Steve wants it that way, I suppose.
Getting music off of your iPod -- the Windows Down & Dirty Method
Unusually enough, this is one place Windows users have an advantage over Mac users. If you have a Windows formatted iPod, Windows actually treats it as a removable drive, and you can go in and copy the files off if you know where to look.
Here's how:
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
Once you've done that, iTunes should sort out the files from the iPod folder structure, put the artist and album information back from the ID3 tags in the music files, and reorganize the whole thing in the iTunes library folder.
The one caveat with this is that what you won't get back is any "metadata" that isn't stored in the files themselves, such as ratings, play counts, last played and modified information, etc.
It's also very difficult to select individual files or groups of files doing this, as it's not terribly obvious which file is which just looking at them in the way the iPod stores them.
Last but not least, I've never seen (nor read about) this trick being tried with any of the "new" iTunes data types, such as pictures, video, games, etc., so I don't know how well it would work to retrieve that information, nor whether this will retrieve purchases from iTunes Music Store intact.
For more methods of copying data off of your iPod, including links to several free utilities that can copy all of your data, please see:
http://www.articleco.com/Article/How-to-Copy-Music-OFF-your-iPod/30006
