Artcyclopedia is an online fine art search engine and "guide to great art on the internet." The site focuses mostly on painting and sculpture, but also includes some decorative arts, textiles and other artistic media. The site contains brief biographical sketches of artists and the movements they are associated with as well as links to other resources about each artist, including gallery and museum sites. A nice place to start when looking for information about an artist and artwork. The site does not contain pricing or auction information; artnet.com has a database of auction and gallery pricing information.
Artists by movement: Dada