Music Player Daemon (MPD) is a server that allows remote access for playing music in various formats and managing playlists. It makes a great desktop player with frontend options (Qt, GTK, ncurses, Windows, and Web clients are available). It is also appropriate as a console player that is scriptable, and is especially useful if X is restarted frequently. A set of rapid development tools for clients are being developed and include a C library, Python module, PHP class, Perl module, and Java Class. The goals are to be easy to install and use, to have minimal resource requirements, to be stable and flexible, and easy to interface.
Goggles Music Manager is a music collection manager and player that automatically categorizes Ogg Vorbis, FLAC, MP3, MP4, ASF, and Musepack files based on genre, artist, album, and song. It supports gapless playback, features easy tag editing, and allows scrobbling tracks to last-fm.
MOC (music on console) is a console audio player with a simple ncurses interface in playmp3list style. It supports MP3 (with ID3 tag, VBR, and Xing headers), Ogg, FLAC, WAVE, Musepack, Speex, WMA, MP4, AAC, and some other less popular audio formats. Playlists can be saved and loaded using .m3u files (PLS version 2 can also be loaded). Internet streams (Shoutcast, Icecast) are supported. It achieves gapless playback by employing an output buffer in a separate thread and file pre-caching. The key mapping can be fully customized. The interface can be detached from the server as it plays in the background.
PyKaraoke is a karaoke player which supports the CDG (MP3+G, OGG+G), MIDI (.KAR, .MID), and MPEG formats. The project consists of a GUI frontend and separate pycdg, pykar, and pympg player modules. The GUI provides a full application frontend, with playlist functionality and a searchable database. The pycdg, pykar, and pympg modules can also be used as standalone command-line players or imported into any Python programs that would like CDG, MIDI/KAR, or MPEG playback.
Aqualung is an advanced music player originally targeted at the GNU/Linux operating system, and also running on FreeBSD, OpenBSD, and Microsoft Windows. It plays audio CDs, Internet radio streams, and podcasts as well as sound files in just about any audio format, and has the feature of inserting no gaps between adjacent tracks.
Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.