The National Archives and Records Administration
The National Archives and Records Administration provides the full text of the Constitution, biographies of each of its signers, and high-resolution images of the document itself.
The Internet Encyclopedia of Philosophy
The Internet Encyclopedia of Philosophy provides a biography of John Locke, as well as a review of his important works.
The American Revolution
This site, the companion to a PBS series on the American Revolution, provides a comprehensive account of the Revolutionary War, including timelines, accounts of battles, and biographies of key figures.
The Avalon Project
The Avalon Project at Yale Law School presents online all 85 Federalist Papers, which can be searched by keyword.