Yes -- atheism. And by extension disbelief in the supernatural. It's the first consequence of acquiring better thinking practices. However, it is not as if atheism in itself forms a good secondary basis for discussion in a rationalist community, since most of the activity would necessarily take the form of "ha ha, look how stupid these people are!". I would know; been there, done that. But it gets very old very quickly, and besides isn't of much use except for novice apostates who need social validation of their new identities. From that point of view I regard atheism as a solved problem and therefore uninteresting.

Nothing else seems to spring to mind, though -- or at least no positive rather than negative positions on ideological questions. "Don't be a fanatic", "don't buy snake oil", "don't join cults", "check the prevailing scientific paradigms before denying things left and right [evolution, moon landing, the Holocaust, global warming etc.]"... critical thinking 101. Mostly all other beliefs and practices that seem to go hand in hand with rationalism seem to be explainable by membership of this particular cluster of Silicon Valley culture.