Harry Potter and the Methods of Rationality

I don't normally read fan fiction but Harry Potter and the Methods of Rationality is excellent. "Petunia married a professor, and Harry grew up reading science and science fiction. Then came the Hogwarts letter..." As well as giving a new, highly entertaining perspective on the Harry Potter universe, it introduces various methods of thinking rationally (more of which can be read at the author's Less Wrong wiki).

Smoke Machine

Found at www.overclockers.com.au

Invisible Trenchcoat