Crap Detecting on the Internet

One of the qualities that we all need in life is a "built in shock-proof crap detector". It makes for good librarianship, there is an article on the BBC website entitle; Warning sounded on web's future. The author says people need a way to separate rumor from real science. This is where we come in, how do we determine the credibility of a web site? We have all had our web evaluation classes. What do you look for, or have we been lulled to sleep by all the crap that's out there on the web?