Well, I am avid fan of books, mainly Science Fiction and Fantasy books, and I run a website (http://critic42.wordpress.com/) for reviewing books.
Q&A for science fiction and fantasy enthusiasts
Q&A for authors, editors, reviewers, professional writers, and aspiring writers
Q&A for professionals and students of engineering
Q&A for passionate videogamers on all platforms
Q&A for professional and enthusiast programmers
Q&A for people studying math at any level and professionals in related fields