artlex.com - Reference material in art, art history, art criticism, aesthetics, and art education. Definitions of thousands of terms, illustrations, quotations, and links to other resources.
The Getty Provenance Index - Collects and disseminates information related to the history of collecting and the provenance of individual works of art.
Resources in Art History for Graduate Students - This newsletter lists grants, fellowships, internships, conferences, publication and study abroad opportunities for graduate students in art history and closely related areas.
About.com: Art History - Online community and resource guide for the artists and art periods of the past.
Art History at Loggia - Explores the history of art with information about artists, styles, and periods. Includes resources and reference materials about art history, searchable database, and forums.
Mark Harden's Artchive - An art archive with thousands of images that are accessed through an alphabetical list of artist's names and art styles. Covers every style of art from ancient and African to impressionist and modern.