The Moog EP-2 is an excellent and inexpensive tool you can get to dynamically change parameters on Moogerfooger pedals and more. It works with Boss pedals and destroys the Roland EV-5, which costs twice as much.
The carrier oscillator in the Moogerfooger Ring Modulator can be reset by an outside audio source. Here it is being done with the Moogerfooger FreqBox (with additional voltage control!) and an Etherwave Standard theremin.