Anders Sandberg summarizes the Global Catastrophic Risk Conference:
I agree with a lot, disagree with some (two that jump to mind: I disagree with making sure existing nomads are self-sufficient instead of creating deep mine communities, I disagree that current probabilities of various disasters are currently low), but there's plenty of good epiphany material in there. Adding to mine communities, self-sufficient communities on the moon, and Mars (in orbit Gerard K. O'Neil style, too, but that would probably be an unecessary redundancy) seem like no-brainers.
Also, I like completely culturally isolated communities, and completely quarantined communities, as protections against existentially threatening memes or biological epidemics. These wouldn't have to completely overlap with deep mines (which are protections against environmental disasters, but seem most optimally designed as protections against gamma ray blasts).