There are many arguments for why gaming has been beneficial to humanity, e.g. improving hand-eye coordination and problem solving.    These days, the ridiculous GPU technology found on modern graphics cards tends to be my favorite such argument.  The pressure to speed up and parallelize the computations associated with the rendering of virtual scenes has lead to what are essentially $500 supercomputers.   CUDA in particular has made this technology accessible to an ordinary C programmer.  Personally, GPU acceleration has led to a couple orders of magnitude increase in simulation and image processing throughput, while many others have reported similar experiences.   I anticipate that advances in GPU acceleration, probably funded through the demands of gaming, will subsequently push advances in most of the basic sciences and medicine.  Exciting!
 
This is not to say I'm not giddy thinking about when PhysX-like technology becomes the norm in games.  That will be a glorious time.