Harry Potter and the Methods of Rationality, by Eliezer Yudkowsky
It sounds crazy, but as someone who reads a lot of fiction (and very little fan fiction, because most of it's crap), I sincerely think this is one of the best things I've read in years. I'd personally rank it up with Asimov or Heinlein at their best.If you're the kind of person, upon discovering a 'wizarding world' would:- Look into establishing arbitrage between the wizards' fixed ratio of Gold/Silver currency and the muggles' variable ratio-Try to discover the underlying laws and mechanics of magic-Use a time machine to prove/disprove P == NPRead this Book!