OS X 10.8 or later only. This script will export the artwork of the selected tracks (or the tracks in a selected playlist) as an image file to the folder which contains each selected track's file--presumably the track's Album folder--or a single user-selected folder. If multiple album tracks are selected, the script will make sure only one artwork file per Album is exported.
Also see Save Album Art as folder.jpg.
This Preferences pane for the script remembers your settings between uses.
Gather audio tracks whose files contain no artwork metadata
Change file type to make selected AACs bookmarkable
Set choice of various number tags of selected tracks incrementally
Deletes the lyrics of every track in the Music playlist
Batch set new Last Played/Last Skipped of selected tracks
Export artwork of selected tracks to parent or specified folder