Clearly the earlier material is more important than the later. Include stuff like "The Bottom Line," "Update Yourself Incrementally," "Think Like Reality," "Conservation of Expected Evidence," "Avoiding Your Belief's Real Weak Points," the Fake Utility Functions sequence, &c. Also consider including the material between "But There's Still a Chance, Right?" through "0 and 1 are Not Probabilities," and "Mind Projection Fallacy" through "If You Demand Magic, Magic Won't Help." Ooh, and reprint the "Twelve Virtues"!
Don't mention quantum mechanics or the Singularity. Don't mention morality except for something along the lines of "Feeling Rational."
These are good suggestions, though if you are going to print "0 and 1 are Not Probabilities" (which makes a coherent argument even though I disagree with it), I would suggest also printing the post where you caution people against putting the label "probability estimate" on brown numbers.
Followup to: The Most Frequently Useful Thing
What's the number one thing that goes into a book on rationality, which would make you buy a copy of that book for a friend? We can, of course, talk about all the ways that the rationality of the Distant World At Large needs to be improved. But in this case - I think the more useful data might be the Near question, "With respect to the people I actually know, what do I want to see in that book, so that I can give the book to them to explain it?"
(And again, please think of your own answer-component before reading others' comments.)