Mr. Voice is a specific-purpose Perl/Tk front-end for an MP3 database. It was written to provide an easy-to-use MP3 solution for the production booth of an improv comedy troupe, and as such is tailored to providing quick searches and playback of MP3s that are split up into categories. While not intended to be a standalone desktop MP3 player, others in a similar situation may find it useful.
Paloma is a program to manage an SQL database of digital music files, and facilitate their retrieval and playback in interesting ways. It works with music files of any form -- MP3, Ogg Vorbis, MIDI... whatever you've got a player for. Paloma makes it easy to rip your entire CD collection and store it on your hard disk (or a collection of CD-Rs) for instant random access; playlists can then be generated using arbitrary SQL commands.
madman is a music manager application in the vein of Apple's iTunes and its many clones. It serves as a tag editor, a media library, and a CD burning frontend, and is extensible through plugin scripts. Dynamic playlists and powerful search features allow you to listen to better music all the time.
mp3act is an AJAX-based Web interface to a user's collection of MP3s. It features Jukebox Mode (play on local stereo), Streaming Mode, a searchable database, easy installation, a simple user interface, reading of ID3 tag data, dynamic playlists, random streams, random play by artist, genre, or album, browsing of the collection by artist or genre, album art downloading through Amazon API, AudioScrobbler submission, and detailed play statistics.
LiMpOo is a multimedia player platform based on a Linux system using a Perl engine. It features playback of MP3 files (with playlists), CD audio (with CDDB lookup), and support for encoding, LCD, and IR. It uses MySQL for speed improvements. A PHP front-end helps to maintain all playlists.