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
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downloaded 1m 48s ago
Locates pairs of track entries pointing to the same file
downloaded 13m 52s ago
Re-locate files of selected tracks to new folder, preserve track meta-data
downloaded 20m 57s ago
Copy chosen tag info from one set of tracks to a different set of tracks
downloaded 22m 32s ago
Rename selected tracks' Song Names with their filenames (minus extension)
downloaded 25m 8s ago
Put filename to comments
downloaded 26m 12s ago
Load this script in your Login Items to activate an iTunes playlist at startup