A lot of international topics, which isn't the focus of this project, but the U.S. articles are excellent as well. The Economist has a policy of not having individual authors sign each article, so don't worry if you don't see an author's name. This is a highly regarded periodical.
ProPublica is a nonprofit news agency founded and run by former New York Times and Wall Street Journal editors and journalists. Its purpose is to promote unbiased, investigative journalism in a time when many news agencies are only printing sensational stories, "the stuff that will sell." Very interesting site!