ArtWonk

From Algorithmic Arts:

ArtWonk is a MIDI and graphics program that produces MIDI music and paint graphics based on algorithmic rules that you interactively create by connecting modules (graphical objects that represent functions and processes) in real time, adjusting the parameters as you go. Not with a set of canned me-too rules and riffs, but with an open ended palette of some 200 composing modules that powerfully boosts your full potential to realize your individual creativity.

ArtWonk will drive MIDI synthesizers, soft synths and sound cards directly, effectively "playing" them in real time or optionally responding to user or environmental parameters; it will also record directly to a standard MIDI file. Real time paint graphics can be created and manipulated on the fly; and both music and paint can be created together as a synesthetic whole.

While you can easily create analog synthesizer style step sequencers with ArtWonk, it goes far beyond its sequencer roots, to give you algorithmic composing tools of all kinds. ArtWonk is essentially a program language specialized for creating music and visuals, intended to be used by artists and musicians. It is not a text based language like Java, C, or Lisp; instead it is a visual direct manipulation language that does not require you to take weeks to months to learn. You simply select graphical modules from a pop up menu, drag and drop their connections and interactions, listening to the results in real time as you build and modify your piece.