A virtual dictionary of art terms with links to other sites:
http://www.artlex.com/

Artweb-an incredible collection of information on everything about the history of art:
www.bc.edu/bc_org/avp/cas/fnart/Artweb_noframes.html

Professor Chris Witcombe of Sweet Briar College selects his favorite art history sites:
http://witcombe.sbc.edu/

Concha's Art Histroy Links-in several languages, rated thumbs up, thumbs down:
http://members.aol.com/concharw2/index3.htm

A virtual Museum, with links to many real ones:
http://www.artmuseum.net/