Hard facts only to be found here - if you can call Dark Age Records that. Produced by Dr. Howard Wiseman. Saxon Shore Dark Age site covering the Historical Arthur. Smart graphics and lots of goodies. The quarterly Journal of the International Arthurian Society-North American Branch.
Some entries are a bit limited, but all are nicely linked together.
A must for the serious researcher. Indispensable searchable archive of past discussions on the Arthurnet. Camelot Project Arthurian texts, images, information, etc. Particularly notable is the complete translation of the Gododdin. This site has very quickly become one of the major Arthurian players on the Web.