The Douay-Rheims Bible - A Catholic translation of the Vulgate Bible into English, often closer to the Latin text that medieval authors would have known than any more modern translations, Catholic or Protestant. If a student can't read the medieval Latin Vulgate itself, this is the translation to use. Also available at Intratext Library, which contains a built-in concordance for many of the words.
The Catholic Encyclopedia - An excellent first stop for research into Catholic doctrine and the history of the medieval Catholic Church.
ORB: The Online Reference Book for Medieval Studies - ORB is an academic site, written and maintained by medieval scholars for the benefit of their fellow instructors and serious students. All articles have been judged by at least two peer reviewers. Authors are held to high standards of accuracy, currency, and relevance to the field of medieval studies.
Medieval Sourcebook - Fordham University's website with links to translations of many medieval texts.
The Labyrinth - A prime site for all medieval resources on the World Wide Web.
Citing Electronic Sources - A collection of links to websites with guidelines for citing material from the World Wide Web, CD-ROMs and other electronic sources. The emphasis is on MLA format, but there is information for APA, Chicago, and Turabian, as well.