BallSequencer is based around the idea of MIDI notes 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. It can be effective for quickly generating percussive or melodic patterns.
You can have 1-6 balls bouncing around in the rectangle at any time, each ball has it's own horizontal parameter strip, and an associated color.