Emulate Drag Playlist Folder to Make New Playlist
You can use the "Duplicate" option in a playlist's contextual menu to make an exact copy of the selected playlist. This works for regular and Smart playlists. You can also select a playlist and drag it in the Playlists section of the Source list to duplicate it as a regular playlist. Using this method will duplicate any kind of playlist as a regular playlist. This is especially useful for making a playlist from a Playlist Folder, which does not have "Duplicate" in its contextual menu.
But you may find it easier to run a script on a selected playlist to duplicate it, especially if you aren't wild about the drag-and-duplicate method which can be slippery. The script below will duplicate any selected playlist as a regular playlist. The new playlist will have the same name as the selected playlist, but you can edit this to include " copy" or something if you wish:
tell application "iTunes"
set selectedPlaylist to view of front window
set newPlaylist to (make new playlist with properties {name:(get name of selectedPlaylist)})
duplicate tracks of selectedPlaylist to newPlaylist
reveal newPlaylist
end tell
(The last command to reveal selects the new playlist; you may not want this.) Name it whatever you like and Save it as a compiled script in ~Library/iTunes/Scripts/. I've found this very handy for making playlists from Playlist Folders that contain several playlists (or sub-Playlist Folders of playlists). Works great with a keyboard shortcut.
UPDATED: Playlist Manager v1.1
Playlist Manager v1.1 can perform common useful tasks on a multiple selection of playlists: rename (add text, remove text, search and replace text), toggle repeat and shuffle, duplicate, delete, export, merge.
This latest version fixes a problem with renaming playlists that are contained in Playlist Folders and now allows "blank" to be used as the replace text in the Search and Replace tool.
NEW: Playlist Manager
I create, reuse, and recycle playlists frequently and my playlists rarely remain static. A hindrance in my playlist management is the inability to select more than one playlist at a time to, say, delete or rename them. Well, I got around to fixing that with Playlist Manager.

This applet can perform common useful tasks on a multiple selection of playlists: rename (add text, remove text, search and replace text), toggle repeat and shuffle, duplicate, delete, export, merge.
UPDATED: Remove n Characters From Front or Back v4.6
Remove n Characters From Front or Back lets you delete a specified number of characters from either the beginning or the ending of the Song Name, Album, Artist, Comments, Composer or Show tag (or their "Sort" siblings) of each selected track. For example, delete the initial digits and the space from "01 First Track", "02 Second Track", and so on.

This updated version caps the maximum number of characters to the length of the shortest text in the selected tags, preventing inadvertent deletion of tag text that may be shorter than the user-set number of characters to remove.
iTunes 10.7 Released
Apple has released iTunes 10.7which is not the version unveiled at today's event to be released in October. This modest update contains support for iOS 6 and the new iPod models.
UPDATED: Search-Replace Tag Text v3.3
Search-Replace Tag Text v3.3 performs a search-and-replace with the text in your choice of tag (Song Name, Show, Artist, Album Artist, Album, Composer, Comments, Genre, or Grouping) in the selected tracks or all the tracks in the selected Playlist. Features case sensitivity and whole word match options and dry run preview.

The latest version sports conventional search fields and has some minor code tweaks.
UPDATED: Drop to Add and Make Playlists v2.2
Drop to Add and Make Playlists v2.2 will accept a single dropped folder containing media files and will add each file to iTunes and then distribute the tracks to playlists named using your choice of the tracks' "Artist - Album" tags or the name(s) of the folder(s) containing the file.
This latest version fixes a problem with trying to process files that cannot be added to iTunes.
TrackSift is a Mac Gem
I think I'll take the day off! Macworld reviews TrackSift as a Mac Gem and awards it four mice. Thanks!
AppleScript Save Changes in Mountain Lion
I've been meaning to post this for the record. Shane Stanley has written up How Mountain Lion Changes the Rules for AppleScript at TidBITS. He explains how scripts and AppleScript applications can be saved in an uncompiled state. If you distribute or system manage AppleScripts and develop on Mountain Lion you really should be aware of these changes.

