RipIT is a command line program for ripping, encoding, and tagging MP3s that needs no user intervention. It is a wrapper for dagrab, cdparanoia, cdda2wav, LAME, Ogg Vorbis, Flac, Faac, Musepack, Wavpack, mp4als and ffmpeg. It supports the retrieval and submission of CDDB and MusicBrainz entries and cover art.
Zinf is an MP3/Vorbis/CD audio player with jukebox capabilities, formerly known as FreeAmp. It features both graphical (with themes) and text-based user interfaces, a download manager for automating MP3 downloads, and a powerful music browser/playlist manager. Other features include HTTP/RTP streaming playback with HTTP stream saving and title streaming, and a fast, clean-sounding Open Source decoding engine. It supports Win32/OSS sound systems, ALSA, and EsounD.
xmms-crossfade is an output plugin for XMMS. Its main feature is automatic crossfading. It also removes the gaps between tracks, to play whole MP3 albums without any audible interruption. xmms-crossfade supports OSS via a builtin driver, and any other platform by using existing output plugins. As of version 0.3.9, the Audacious media player is also supported.
MuSE is a user-friendly tool for network audio streaming, making life easier for independent free speech radio stations. It can play, mix, encode, and stream sound from and to the Internet in both MP3 and Ogg/Vorbis format to be listened by the majority of audio players. It can simultaneously mix up to 6 encoded audio channels plus a sound card input signal, sending the result to an Icecast/Shoutcast server. It offers GTK2, ncurses, and Carbon (OSX) interfaces for real-time operation and a full set of command line options.
XMMS2 is a redesign of the XMMS music player. It features a client-server model, allowing multiple (even simultaneous!) user interfaces, both textual and graphical. All common audio formats are supported using plugins. On top of this, there is a flexible media library to organize your music.
Quod Libet is a music library management program. Rather than categorize songs by genre, artist, and album, it lets you search and display them however you want. It supports regexp-based searches, album cover display, tag editing, ReplayGain, multimedia keys, and an OSD. Also included is Ex Falso, a tag editor that has the same editing features found in Quod Libet, but does not play audio files.