I feel I've learned a lot about problem solving from less wrong (and HPMOR in particular). be concrete, hold off on proposing solutions, et cetera. The effect*, unfortunately, doesn't seem to be as much as I had hoped.
Small increases in intelligence are extremely general and even recursive, so it feels worth the effort. But, I found alternatives much more effective (though still modest) then studying/discussing/applying the sequences. like meditation or smart drugs.
I'm interested in other lesswrongers experiences in cognitive enhancement.
* by "smarter" I mean "better at problem solving", where examples of "problems" are writing a program, finding the right thing to say to resolve interpersonal conflict, memorizing some random fact quickly and then recalling it quickly/vividly. let me know if you want further clarification.