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.)
Enter text for the selected tracks' Category tag
Set choice of various number tags of selected tracks incrementally
Delete and trash tracks from iTunes whose play counts are 0
Exports and then re-imports selected tracks' artwork
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
Remove iTunes tracks disassociated from files