This script will re-embed artwork downloaded from the iTunes Store into the files of the selected tracks.
Also see Re-Embed Artwork.
NOTE: this script cannot handle processing more than about an album's worth of tracks per launch due to the way iTunes manages the graphics data.
Note: (August 2014) Not sure what the issue is but results are inconsistent with modern versions of iTunes.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using Script Editor (AppleScript Editor pre-OS X 10.0) which is located in your /Applications/Utilities/ folder. More information is here.)
Perform search-and-replace on text in your choice of tags
Renumber order of selected tracks
Perform tasks on a batch of playlists; rename, delete, duplicate, merge, more
Displays files in iTunes Media folder not in iTunes track library
Copy files of tracks to selected folder
Display, create text file listing info of dead tracks