This applet will assist with swapping, copying, and appending data between two user-chosen tags in selected tracks or tracks in the selected playlist:
Swap - swap data between tags, ex: ARTIST<->COMPOSER
Copy - copy data from one to another tag, ex: ARTIST->
Append - append data from one tag to the end of another, ex: ARTIST->COMPOSER - ARTIST
Prepend - prepend data from one tag to the beginning of another, ex: ARTIST->ARTIST - COMPOSER
The latter three actions also provide an option to delete the info from the first tag after the copy. Read Me explains all.
For OS X 10.8 or later only. This update is free for registered users of v4.x.
Select the Action to perform between the two chosen tags in each selected track.
Export selected playlists as individual XML or M3U files
Copy chosen tag info from one set of tracks to a different set of tracks
Convert selected tracks and export the converted files to a new folder
Display, create text file listing info of dead tracks
Batch-append text to comments
Remove iTunes tracks disassociated from files