http://www.artcellarex.com/ace/
The Art Cellar Exchange is an art consultancy group for people who would like to buy or sell fine art. In their Electronic Classifieds they list art that is currently on the secondary market alphabetically by artist name or work title. Listings include medium, edition number, retail and asking prices, and some include pictures of the art itself. Also included is an Art Wanted page, an Ad Form for people who would like to place ads to sell their art, and a Request Form to search for specific art pieces.