Contributing to Free Software projects, especially scientific ones, could be the best use of time for a lot of rationalists.
And (allowing for politics being The Mind Killer and all that) cause- or issue-based political campaigning. For example the current campaign to introduce the Alternative Vote for UK General Elections is a pretty clear example of something where there is an obvious rational and irrational side (AV allowing more information into the system, providing better feedback).
Contributing to Free Software projects, especially scientific ones, could be the best use of time for a lot of rationalists. And (allowing for politics being The Mind Killer and all that) cause- or issue-based political campaigning. For example the current campaign to introduce the Alternative Vote for UK General Elections is a pretty clear example of something where there is an obvious rational and irrational side (AV allowing more information into the system, providing better feedback).