Claremont Colleges Digital Library: Includes prints by Goya and other important works of art.
The Getty Research Institute: Digital database for works of art, photographs and art related research.
Web Gallery of Art: Good reference for lots of art history images.
University of Washington Libraries: Digital collections.
All Together Now: A digital collaborative and interactive music project.
Art: 21 - Companion website to the DVD series. Some episodes available to view online.
Good general art site, mostly image links to museums.
Canva Color Wheel
Explore color theory and color combinations
The Design & Publishing Center
Design, typography, graphics, illustration, writing, printing, publishing, advertising, signs and displays for graphic communicators.
Google Images: A comprehensive search engine for images.
Prints and Photographs Division
Advertising and Propaganda, American Memory Project, Library of Congress which comprise an estimated 13.7 million items.