An extensive resource for many aspects of Medieval Studies, the Internet Medieval Sourcebook provides access to English translations of important Medieval texts spanning from the end of Rome to the Reformation. Texts are listed chronologically and thematically. The site also provides links to relevant online resources and provides useful information for students on writing about history.
Sponsored by Georgetown University, The Labyrinth is a collection of resources for Medieval Studies. The site is organized according to category (e.g. Architecture, Arthurian Studies, Drama, Medicine, etc.), with each category providing related links. Conveniently, and in contrast to many other generalized sites, The Labyrinth provides short yet effective annotations for most of its links.
A database of Medieval resources, this site provides categories that are organized according to fields (e.g. Archaeology, Art, Philosophy, Religion, etc.), with multiple links available from each field. Also available on this site is a useful Medieval glossary. The layout of this site is somewhat chaotic, which may deter some users.
The Voice of the Shuttle is a gateway to research in the humanities. It offers extensive lists of sites geared towards most disciplines in this field, including Art History, Literature, Music, Archaeology, and Classical Studies. Although not specifically geared towards Medieval Studies, the site does contain many links that relate to the Middle Ages.