Audio recording and editing suite with support for CD mastering and non-linear processing. Site includes screenshots, downloads, developer information, and forums. (C++) [Cross-platform]

Audio player with support for many different file formats, last.fm, replay gain, and metadata editing. Site includes downloads, screenshots, and developer information. [Mac]

A web server for streaming music from iTunes over a network. Site includes downloads, forums, demonstration server, and project information. [Cross-platform]

Music collaboration software for having realtime jam sessions over the Internet. Site includes description, software download (with source code), forum, and servers for collaboration. (C++) [Cross-platform]

Audio player featuring playback of multiple formats, tags, and last.fm scrobbling. Site includes downloads, feature list, screenshots, forum, and development information. [Mac]

Music score editor, sharing some of the same developers as NoteEdit. Site includes a wiki, downloads, feature list, bug tracker, and development information. (C++) [Cross-platform]

Music composition and notation software. Site includes downloads, screenshots, manual, forum, and development information. [Cross-platform]

A tracker written in Python, designed to be very similar to Jeskola Buzz. Site includes forum, screenshots, bug tracking and source-code download. [Linux]

MP3 analysis tool that also includes file correction and tag editing. Site includes downloads, screenshots, user manual, and development information. (C++) [Linux, Windows]

Application to manage lyrics, chords, lead sheets, overheads, and computer projection. Website includes additional packages such as song, background and language packs, documentation and a support forum. (REALbasic) [Cross-platform]