Harry Potter and the Methods of Rationality, by Eliezer Yudkowsky
It sounds crazy, but as someone who reads <i>a lot</i> 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.<p>If you're the kind of person, upon discovering a 'wizarding world' would:<p>- Look into establishing arbitrage between the wizards' fixed ratio of Gold/Silver currency and the muggles' variable ratio<p>-Try to discover the underlying laws and mechanics of magic<p>-Use a time machine to prove/disprove P == NP<p>Read this Book!