That is actually something I have been thinking about recently. People spend hours upon hours playing games that resemble, to some degree, real jobs. (Think FarmVille, CafeWorld, etc.)
If you could craft the game in such a way to provide the control to the robots for things that are not easily automated, people's entertainment would provide the labour required to control the operation for free. A capitalistic dream.
Sorting recycling comes to mind. The manual labor version of it involves standing over a slow moving belt of stinky trash and picking out the valuable recyclables.
Seems like a Fanuc with a suction gripper and a hires web cam is all it might take to get a little "trashville" going. Give the housewives who collect the most alu while the kids are away at school day passes to local spas as prizes and you've got a win.
The tricky bit would be designing an interface for turkers to manipulate the robot.
The other complicated bit is making sure the turkers can't cause serious harm. (We don't want turkers controlling UAVs...)