Subscription-based services are available through the University Library Web site including ARTStor and AMICO. ARTStor is an initiative of the Andrew W. Mellon Foundation and currently offers approximately 300,000 images including an Image Gallery, drawn from the slide collection of the University of California at San Diego, and Special Collections including the Carnegie Arts of the United States, the Architecture and Design Collection of the Museum of Modern Art, the Illustrated Bartsch, and the Mellon International Dunhuang Archive.  AMICO is the Art Museum Image Consortium containing more than 100,000 images contributed by American Museums such as the Museum of Fine Arts, Boston, the Cleveland Museum of Art, The Whitney Museum of American Art. 

Visual Collections: Images of Art, History, and Culture
CU: E-Images
Google: Images