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.)
Export album artwork as folder.jpg to Album folder
Change the label color of the files of the selected tracks
Exports and then re-imports selected tracks' artwork
Batch-append text to comments
Paste text contents of the clipboard to each of the selected tracks' Lyrics tag
Create a Ringtone track from a selected track