Real-time audio synthesis engine and music programming language
N.B. SuperCollider is now hosted at GitHub, and the most recent versions can be downloaded from there. http://supercollider.github.io A real time audio synthesis engine, and an object-oriented programming language specialised for music. SuperCollider was created in 1996 by James McCartney, now (since version 3) released as free software.
Nyquist is a language for sound synthesis and music composition. It is implemented in C and C++ and runs on Win32, OSX, and Linux. Nyquist combines a powerful functional programming style with efficient signal-processing primitives.
Relational programmable database with GUI
MUIbase (Magic data BASE with User Interface) is a relational programmable database with user interface for Windows, Mac, Linux and Amiga.