If you run Firefly Media Server, you can run this script to create an M3U of all the tracks on your server. You can play this in most audio players; VLC likes it, as does iTunes (though big playlists take an age to load). Rhythmbox and the default Ubuntu Movie Player won’t touch my playlist of over 17,000 tracks.
To configure the script you need to edit three lines:
# where the Firefly database lives
# server domain name or IP address
# Port to talk to server - don't leave blank
If you’re running Ubuntu, you’ll probably only need to change the SERVER line. It spits the M3U playlist, ordered by album, to stdout. Note that in the default Ubuntu install, regular users can’t read the database file.
If you’re running this from a cron job, it’s probably a good idea to fill in the real paths for sqlite3 and awk.