I use a propane torch on the back side of the board, and smack the board down on the edge of an empty 5 gal bucket, so the bucket catches the parts and the solder splashes.
There is an electronics surplus company nearby that I frequent to find test equipment. Most of what they have in there is destined for China where they salvage the components off of the boards for repackaging and resale. That is how they pull the components off of the boards overseas. It is very quick way to do a large number of components and boards in a short amount of time.
You could even fill the bucket with water as most components do not mind taking a bath. That would keep the solder splashes from making a nasty mess that glues all of the components together in the bucket.
You definitely want to be wearing goggles, a long sleeved cotton shirt, leather gloves and have burn creme nearby. It takes about 2 minutes to remove most of the components from the board.