At History is a Weapon a brief audit of the role of bias in history begins, "History isn't what happened, but a story of what happened." That much should be obvious, but is worth hearing from time to time. The audit offers quick entry into some of the central questions of historiography, and stands as the welcome page to a website that presents scanned versions of several texts, including A People's History of the United States. History is a Weapon describes itself as "an online Left reader focusing largely on American resistance history." I think that's an accurate assessment for a site that is a terrific resource.
I've added a link under "American History Links."