UplandToys BallSequencer is a sequencer based around the idea of MIDI messages being generated by balls moving around inside a rectangular area. Notes are triggered whenever a ball collides with the boundary of the rectangle. You can set parameters that will control the movement of each ball, in addition to possible note and velocity values depending on which wall is hit. All parameters have a brief explanation which can be viewed by opening the live help window and hovering over the parameters.
Pricing and Availability:
Gaz Williams has one and he brought it round