Retrieving Files From iPod Shuffle
You can't drag tracks from the iPod Shuffle playlist to the desktop, like you can with regular iTunes playlists. But AppleScript can do it.
The iPod Shuffle Source
If you have an iPod Shuffle "registered" (for lack of better terminology) on your Mac, then you have a permanent iPod Shuffle playlist in your iTunes Source column. This is what Apple calls a "special playlist". When you plug the Shuffle in, it updates its contents based on the tracks in the iPod Shuffle playlist. It's a closed system: the only files that can go to the iPod Shuffle are the ones in the iPod Shuffle playlist.
Unfortunately, you cannot directly access the audio files on an iPod Shuffle. Nor are you able to select tracks in the iPod Shuffle playlist and drag their files to the Finder like you can with regular iTunes playlist tracks.
I ran into this when I wanted to preserve the audio files on an iPod Shuffle because I was going to "register" it to another computer. See, if you want to register the Shuffle to another computer, you have to erase the Shuffle's contents. And you can't share files on the iPod Shuffle between different computers. (This is mentioned in the iPod Shuffle FAQ at Apple.) I wanted to make sure that the contents were preserved, so my thinking was to copy the files, move them to the new computer, and re-add them to the Shuffle after registering it there.
Luckily, AppleScript comes to the aid of the party. You can get the location of each track in the iPod Shuffle playlist, which is the filepath alias of each track's file on the registered machine, and use that to copy the file from its current location on the registered machine to a new location. This emulates the drag-track feature nicely. Note that the files are not copied or moved from the Shuffle; they are copied from their original location on the machine the iPod Shuffle is registered on.
The script to use is called "Copy Files to Folder... " in Files to Folder Scripts (written by Derrick Bass), which will copy the files of the selected tracks to a user-selected folder. Just select the tracks in the iPod Shuffle playlist, run "Copy Files to Folder... ", and the files will be copied to a new location you select. In my case, I saved them to a Lacie portable drive; I re-registered the Shuffle on the other computer, then added the preserved files to that computer's iTunes from the Lacie.