OS X 10.8 or later. Append the same user-entered text to the beginning or ending of the existing text in the chosen tag (Song Name, Artist, Album Artist, Album, Composer, Comments, Genre, Grouping or Show Name, and their Sort siblings) in each selected track.
For tags other than "Song Name" and "Show Name", this script may be just slightly less involved than performing a multi-edit on the selected tracks.
Also see This Tag, That Tag.
Preview each track as it will appear after applying the entered text.
Sort purchased tracks into discrete playlists by name or account ID
Add or subtract a user-entered number from each selected track's Plays
Add or subtract a user-entered number from each selected track's Skip Count
Re-associate batch of dead tracks with files from selected folder
Append user-entered text to beginning or ending of selected tag of each selected track
Move selected playlists to a new or existing folder