There are inflatable bladder systems that you can retrofit in residential systems fairly easily. It involves running pneumatic tubing inside the ductwork from the ducts to a central point where they are attached to a computer controlled manifold. At the duct end, the tubing is attached to inflatable bladders that are secured near the end of the duct with a framework. The manifold can then inflate the bladders to block airflow to that duct. The tubes are run with the use of a big fan, blocking all the ducts but the one you're dealing with, a long piece of string, and a small "parachute".