This post is prompted by a short discussion with Wei Dai. He says:
Perhaps we should get other causes to participate/recruit on LW? Actually, why aren't they here already? We have a bunch of individuals with non-SIAI interests, but no causes other than SIAI, despite Eliezer repeatedly saying that they would be welcome.
He has a good point!
Here's my plug, for the cause I spend lots of my time and energy on, Wikimedia/Wikipedia:
Wikipedia/Wikimedia is more analogous to a software project than an ordinary charity - your money is useful and most welcomed, but the real contribution is your knowledge.
Or, more generally: create educational material under a free content licence. If it's CC-by-sa, CC-by or public domain, it can interbreed and propagate.
(Then we need to fix the things wrong with the editor experience on Wikipedia ... though the Wikimedia Foundation is paying serious attention to that as well of late. In the meantime, if you find Wikipedia too personally annoying to participate in directly, writing your own site and CC-by-sa'ing it still helps a lot.)
What good causes can you think of that are relevant to LessWrong and its community, that leverage effectiveness through rationality? (I'm thinking beyond just legally-blessed charities, right down to the "small circle of conspirators" level of trying together to get something done.) As well as SIAI, LW has previously had plugs for GiveWell. What do you spend your time, effort and/or money on?