Okay, so I see two solutions here:

1) put a link to "Rationality" e-book on the LW title page, and maybe also in the sidebar -- for the new users;

2) for the old users -- someone should study something rationality-related, and then post it in a form similar to Sequences (for me that means: motivating and easy to read), adding their own insights. Easier said than done, but this approximately what Sequences were about.

None of this seems related to the typical solutions on "improving Less Wrong", but maybe other people are trying to solve a different problem.