OS X 10.8 and later. This script will export then re-import the artwork data of the selected tracks obliging iTunes to embed the artwork in the track's file's meta-data.
For best results, use with an album's worth of tracks at a time.
Note: this app does not affect how the Finder may or may not display a file's icon image.
Also see Tracks Without Embedded Artwork.
Two scripts copy text from clipboard to current or single selected track's lyrics tag
Gather audio tracks whose files contain no artwork metadata
Exports and then re-imports selected tracks' artwork
Export selected playlists as individual XML or M3U files
Set choice of various number tags of selected tracks incrementally
Re-associate batch of dead tracks with files from selected folder