Audio player with support for many formats, and it has support for third-party plugins. Site includes screenshots, developer information, feature list, and downloads. [Linux]

Open Source, web-based audio file manager and player. Site includes bug-tracker, support wiki, downloads, and a live demo.(MySQL and PHP)

Music player which supports album art fetching, Last.fm submission, and plugins. Site includes forum, downloads, screenshots, and themes. (Python) [Linux]

Media player which supports skins and plugins. Site includes downloads, plugins, skins, forum, and developer information. (C) [Windows]

Digital DJ software with features like parallel visual displays, beat estimation, beat matching, skins, and Equalizers. Site includes news, downloads, screenshots, and support information. [Cross-platform]

Now defunct MPEG-4 tools and broadcaster. Site contains screenshots and source-code. [Linux]

Mp3 encoder which reads FLAC and Ogg Vorbis files. Site includes download for binaries, source code, and old versions. [Windows]

Drum-machine for creating patterns-based music. Site contains project news, downloads, example music, forum, and screenshots. [Linux]

Audio workstation for creating digital music. Site includes demo songs, screenshots, downloads, a wiki, and user created songs. (C++) [Cross-platform]

On-the-fly encoder for recording analog audio sources (i.e. line-in or microphone) directly to Ogg Vorbis/Wave/MP3, featuring auto-normalization and command line support. Site includes news, screenshots, forum, and downloads. (C++) [Windows]