I never, ever, thought I’d say this, but:

This is fanfiction, about Harry Potter, and its really, really good.

http://www.fanfiction.net/s/5782108/1/Harry_Potter_and_the_Methods_of_Rationality.

Yeah.  I didn’t believe it either.  But its true.  Way, _way_ better than Rowling’s version, to my mind.