OS X 10.8 or later. iTunes only allows one playlist to be selected at a time. This applet can perform common useful tasks on a multiple selection of playlists: rename (add text, remove text, search and replace text), duplicate, delete, export, merge.
Tools in the Rename tab operate on the selected playlists' names
Append user-entered text to beginning or ending of selected tag of each selected track
Display, create text file listing info of dead tracks
Re-associate batch of dead tracks with files from selected folder
Deletes the current track from all playlists and moves to Trash
Export files of tracks in two or more playlists to single folder
Create a playlist for each entry of a specified tag