These archives from Yale Law School include links to various primary source documents from the September 11 terrorist attacks. The Avalon Project gathers various documents dealing with Law, History and Diplomacy which could be very useful when discussing history, or current events.
An amazing source for declassified United States' documents that could easily be used for primary sources in a modern U.S. or world history classes. These could be used for a in-class debate as the National Security Archive houses many documents on very controversial issues in history. I would also highly recommend looking through them to provide yourself with different prospectives as a future teacher.
This website contains useful information for teachers. Funded by the Department of Education, this website has lesson plans, primary documents, and helpful advice from current teachers.
This site analyzes Boston at before and at the beginning of the Revolutionary War. It includes, commentaries on significant events and people, maps, pictures, and primary sources