These take pre-created playlists and evenly shuffle them together into a new playlist. You can make a "battle of the bands" playlist, alternating between bands. You can shuffle 5 genres (for example, Jazz-Country-Rock-Folk-Metal) so that every 5th tune is a jazz tune. Perhaps you'd like to alternate between new tunes and old tunes, your wife's favorites and your favorites, etc. These scripts make this easy to do.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using AppleScript Editor, which is located in your /Applications/Utilities/ folder. More information is here.)
Display, create text file listing info of dead tracks
Locates pairs of track entries pointing to the same file
Copy chosen tag info from one set of tracks to a different set of tracks
Manage shared tracks over a network
Export info to HTML doc
Exports and then re-imports selected tracks' artwork