"For one, as any flight simulator fan knows, an imaginary world can make a boffo training ground. Tim Allen, head of technology at Crompco Corp., an underground gas tank testing firm, discovered that as the pseudonymous "FlipperPA Peregrine" inside Second Life. There, he built a virtual gas station, graphically showing all the tanks and gas lines under the asphalt. He says it's much easier to grasp the station's workings this way than it is on paper. "It's great for training new hires and showing changing regulations to existing employees," says Allen, who also runs the Web mall SLBoutique."

I've often though of doing an offline "How Things Work" [amazon.com] using a game engine.