OS X 10.8 and later. This script will export then re-import the artwork data of the selected tracks.
Note: This script may not be able to handle processing more than about an album's worth of tracks per launch due to the way iTunes manages graphics data.
Also Note: (August 2014) Not sure what the issue is but results may be inconsistent with modern versions of iTunes.
Restore each selected track's artwork from an image file stored in its Album folder
Use tag info from selected track to search Amazon Books for cover art
Edit a selection of iTunes tracks' tags "old-school"
Displays files in iTunes Media folder not in iTunes track library
Assists with finding truncated iTunes Match tracks
Copy Artist to Album Artist of selected tracks