Internet Medieval Sourcebook: A fantastic collection of original source material, stretching from the late Roman period up to the end of the middle ages. Contains a wide variety of sources including many chronicles as well as much literature from the period.
ORB: The Online Reference Book for Medieval Studies:
The Society of Ancients: an international amateur society for the promotion of the study of ancient and medieval military history
Battle of Fulford - 20 September 1066
- an interesting site that looks at the possible location of the battlefield.