jMax is a visual programming environment for building interactive real-time musical and multimedia applications by allowing the user to interactively design dataflow circuits. The basic data types that can go through are integers, symbols, lists, etc. It is an event-driven system and has been used for MIDI processing. A second part of the system (DSP) allows a continuous signal to flow through a circuit, which is most useful for PCM sound (ie. microphone, sound files, etc.). The system is extensible by using shared libraries, you may add data processor types, data types, GUI elements, device types, and more. Data processors may also be designed as circuits and reused.
Shake Tracker aims to be a fully-featured MIDI sequencer with a tracker interface. It currently works well and supports most tracker effects. Anyone who has used Impulse Tracker before will feel at home, and for the new users, a simple but extensive help system is provided. Most commands and shortcuts resemble their tracker counterparts. Shake tracker compiles on Unix and Win32 systems.
Songwrite is a tablature editor. It supports many string instruments in addition to traditional staff notation. You can edit tablature (guitar, bass, banjo, etc.) and staff notation, add lyrics, create your own songbook, play your partitions, print your partitions and your songs, automatically convert staff notation to tablature and vice-versa, export songs to many formats (PDF, MIDI, ASCII tablature, GNU Lilypond, LaTeX, PostScript, etc.), and import Guitar Pro 3/4 files (experimental).
Swami is an instrument patch file editor using SoundFont files that allows you to create and distribute instruments from audio samples used for composing music. It uses FluidSynth, a software synthesizer, which has real time effect control, support for modulators, and routable audio via JACK. This project supersedes the Smurf SoundFont Editor, and is an entire object-oriented rewrite of it. The supporting libraries are GUI-independant and can be used in your own programs for doing SoundFont manipulation.