Computational complexity theory tries to find equivalence classes of problems that can map to one another. Each class has a primary representative such as TSP (travelling salesman problem) or 3-SAT that memorably capture the essence of the class. While it's not clear that you can map Grand Theft Auto to anything useful, you might be onto something here: Imagine a mechanical turk system where the grunt tasks are remapped onto inherently enjoyable gameplay scenarios. It would be an arbitrage play between turk vendors needing menial tasks done, and players needing entertainment. Recaptcha is a (brilliant) example, but I don't know of others. Maybe UAV control might be one. (Note that mapping one valuable task to another enjoyable task is a different idea than the "gamification" fad of inventing events to adorn with tawdry badges.)

It wouldn't have to be a full time task but could be inserted into a game to provide a change to the flow. For example putting together an iphone from pieces found in an old cardboard box while zombies are trying to break in the door you just locked. This is kind of like the use of in game advertising in that when done well it doesn't actually detract from the game but adds to it.

Just add points to arbitrary tasks and people will do them for free and with unexpected ability. Did you know there are amateur human protein folders and they pretty much outperform computational folders?

Reminds me of a similar idea I had related to remapping body motions from a motion-based control scheme in a game, to real world assembly lines. "Solve the puzzle and get $10 in Labor Points towards your next iPhone!"