This summer, I attended a one-day conference entitled The Digital World of Art History, which was organized by the Index of Christian Art at Princeton University. The papers dealt with a variety of relevant topics including copyright, bibliographic standards, and digital best practices.
The Index of Christian Art is the largest archive of medieval art in the world and the conference offered a fascinating look into their collections and current projects. Although access to the Index is subscription based, I learned about several publicly accessible image databases that the Index has made available on their website for scholarly use. The images in these databases come largely from donated collections and include the Gabriel Millet collection of Byzantine and Early Christian art (over 10,000 images), The Gertrude and Robert Metcalf Collection of Stained Glass, The Mills-Kronborg Collection of Danish Church Wall Paintings, the Tuck Langland Collection (Gothic Architecture) and the Svetlana Tomekovic Database of Byzantine Art.
Conference papers from The Digital World of Art History can be viewed here.