A chronological, geographical, and thematic exploration of the history of art from around the world, as illustrated by the Metropolitan Museum of Art's collection. Includes maps, time lines, thematic essays, and an index.

Images and annotations of nineteenth century Japanese prints by Utagawa Kunisada, Utagawa Kuniyoshi, Tsukioka Yoshitoshi, and Katsukawa Shunsen, exploring "the relationship between men and women."

A lexicon of Art and Science featuring paintings, pigments and scientific methods for investigation of works of art. Includes the stories behind the paintings, history of use of individual pigments, pigment properties and their identification in paintings, and more.

Graphics Atlas is a sophisticated resource that presents a unique, object-based approach for the identification and characterization of prints and photographs.

An e-book on historical, mostly European, painting techniques, from the Getty Conservation Institute, Los Angeles.

An online, open-access platform devoted to the technical study of art objects.

Tons of great links on technique and materials.