Art of Problem Solving

Art of Problem Solving is an online school and community for math nerds and geeks. Its community contains many forums, some which are related to math (e.g. MSM) and some which are not (e.g. Fun Factory). Users can take classes, practice math, post, make online friends, and give/receive upvotes from their posts. The website is also controlled by many site admins (e.g. levans) that make sure users don't spam or post inappropriate stuff.