I can't really recommend a book I've only just started, and Hard-Boiled Wonderland and the End of the World isn't about rationality, nor is it obviously in the majority's tastes here (surrealism, repressed sexuality, unicorns).
But Clippy might like it more than most fiction. Paperclips promise to play some pivotal role in the next phase of evolution or the end of the world.
That's the only book I can think of that has ever made me cry.
This is a place to consolidate book recommendations.
I'm reading The Logic of Failure and enjoying it quite a bit. I wasn't sure whether I'd heard of it here, and I found a post here called Great Books of Failure, an article which hadn't crossed my path before.
There's a recent thread about books for a gifted young teen and a slightly less recent discussion of books on cogsci thread which might or might not be found by someone looking for good books.
So, what books or lists of books do you recommend?