This isn't really a full post, but merely a note of potential interest. Paul Graham (who runs Hacker News) has several very interesting and thought-provoking essays located on his personal website. To me they fit very well with the style of thinking employed and advocated by many people on LW and I'd advise that nearly anyone interested in LW check out his work.
I especially recommend Keep Your Identity Small, What You Can't Say, and What You'll Wish You'd Known, but nearly every essay up there is interesting to me in some way. Many of them are directly relevant to issues of rationality, while others are only indirectly related, but either way I found them worth my time.