[ECarlson]

Some sound and lighting boards have computer controlled presets where the board can return the pots (sliders) to any preset position. Is that the kind of board you are talking about?

I would guess that the pots have either a servo or stepper motor to return them to position. I don't know if the feedback mechanism is the pot itself (most likely, since the OI processing part of the boards are pretty much purely digital anyway), or yet another position sensor. It's also possible that the sliders are not pots at all in some of these boards, and are actually optical position sensors.