Davidson.edu: Visual Agnosia
Gives general definition, with specifics on apperceptive, associative, and mirror agnosia. Includes prosopagnosia and treatment details.
Face Blind
Information on the disorder from the Prosopagnosia Research Center at Harvard University and University College London.
Prosopagnosia Research
Psychology lecturer at Bournemouth University offers background, overview, discussion forum, and information on prosopagnosia research.