http://lesswrong.com/

Interested in improving your reasoning and decision-making skills? Then you’ve come to the right place. We’re an online community dedicated to the study of human rationality, the general field of improving our decisions. LessWrong pulls together a variety of material from mathematics, economics, cognitive science, and other disciplines which can all be relevant when considering how we think. We’re also interested in technology, the long-term future of humanity, and philosophy.