Internet Medieval Sourcebook
Although the Medieval Sourcebook has now become a part of ORB (the Online Reference Book for Medieval Studies), it is often treated separately and still deserves its own listing. It contains thousands of primary documents from the Middle Ages (excerpts and full texts), as well as maps, secondary sources, links to course syllabi, and links to other academic resource sites. There are special sections for "Saints Lives," "Medieval Legal History," etc. The site is searchable.