Art Renewal Center
This organisation promotes the revival of classical realist art. The link leads to their Annual ARC Salon, the most prestigious realist art competition in the world. The artwork presented is from the best living master artists of today.
It is my favourite study and research site and I believe it to be the most comprehensive websites for classical art. Although the ARC has free access to most of its content, their membership offers very high resolution images of almost all artworks displayed, which is excellent for the study of finer details and brush strokes in artwork.