FactCheck.org is a project of the Annenberg Public Policy Center of the University of Pennsylvania, which monitors the factual accuracy of what is said by major U.S. political players in the form of TV ads, debates, speeches, interviews and news releases.
Curious if the URL to a news site is authentic? Ulrichweb will tell you all about traditional publications. You can look up a magazine or newspaper and find out what their URL is ... and even if the publication is peer reviewed!
Each of the following sites provide slightly different methods for thinking about the reliability and trustworthiness of various types of information sources. While the specific questions or points to consider when evaluating sources may differ, they all basically emphasize the same issues. It is important to take these items as a whole...very few are 'deal-breakers;" however, if a source 'fails' the majority of the questions or points, you'd be better off not using it.