Another possibility to use gaming productively is to try to start up a LW- or SIAI-backed MMO and use it to generate revenue. It seems unlikely that this would be practical, but I'm not sure of that, so I figure throwing that idea out there can't hurt.

I don't see any reason why it would be useful for the MMO to be explicitly LW- or SIAI- backed. It should be simple enough for anyone who affiliates with either to simply donate the profits of such a venture to SIAI/FHI/etc. without any of those institutions having to take the status hit of being involved in a video game.