Artcyclopedia: "Our mission is to become the definitive and most effective guide to museum-quality fine art on the Internet:" This site contains a huge database of online art. Excellent for current artists (e.g., Robert Bateman). 

Art Gallery of Ontario: Canadian painting exhibition from 1700-1945.

The Incredible Art Department: Collection of plans, links, and general art stuff!

The McMichael Canadian Art Collection