This is a demo video of a couple of freebies from TubeOhm, Anti-Transpirant 8000 mono and the To-Stepper 4 free.
Anti-Transpirant offers virtual analog sounds and an old-school hardware-style interface. The step sequencer offers 16 steps, with velocity, hold, shuffle and master pitch.
A commercial version is also in the works that will offer polyphonic sequencing, external audio trigger and more.
MIDI up your drums with these aluminium balls