Aims to "provide readers a sense of the political leanings of the source. This makes it much easier to provide different perspectives on any topic, helping all of us see a more complete picture and better appreciate each other despite our differences." Compare the site's rating with the readers' rating for each source.
"We are not just looking at political bias, but also how factual the information is and if they provide links to credible, verifiable sources." Each source also has a poll for readers to submit their own evaluation of bias, so you can compare the site's judgment with the public perception.