Existential Risks

More specifically, topics other than Friendly AI. Groups other than SIAI and FHI that are working on projects to reduce specific x-risks that might happen before anyone has a chance to create a FAI. Cost/benefit analysis of donating to these projects instead of or in addition to SIAI and FHI.

I thought the recent post on How to Save the World was awesome, and I would like to see more like it. I would like to see each of the points from that post expanded into a post of its own.

Is LW big enough for us to be able to form sub-groups of people who are interested in specific topics? Maybe with sub-reddits, or a sub-wiki? Regular IRC/Skype/whatever chat meetings? I still haven't thought through the details of how this would work. Does anyone else have ideas about this?