Harry Potter and the Methods of Rationality.

Oh, I'd been to LessWrong before. I'd read a bunch of Eliezer's stuff here and on his personal site. It was all cogent, important stuff that made perfect since; I'd read a page and understand that the insights would be important to remember for the rest of my life. And then I would close the browser and absolutely forget about it.

It wasn't until I read HPMoR that I truly felt what LessWrong was like. I came back to LessWrong and started devouring the sequences. Every page or two, parts of my worldview would click into place. There were some things I agreed with lots and others not so much, but the good far outweighed the bad.

Been here ever since.