UplandToys has released BallSequencer M4L, a Max 4 Live version of the innovative VST instrument plug-in originally released for Windows in 2006.
The functionality has been simplified compared to the VST-version, but the basic premise remains the same. MIDI messages are generated by balls moving around inside a rectangular area, and notes are triggered whenever a ball collides with the boundary of the rectangle. You can set various parameters that will control the movement and behaviour of each ball.
Price: Free.