It seems to me that Rutgers University somehow has an endless supply of stellar women’s/gender/queer studies online resources. Most recently I heard about Women Artists Archives National Directory (WAAND). WAAND is a web directory of archival collections of primary source materials by women visual artists. The artists featured in the directory are based in the United States and their work spans from 1945 through the present.
Site visitors can either browse the entire directory (1000+ collections listed) or search library-catalog-style. This is an example of one search record — the Joan Flasch Artists’ Book Collection, found by a keyword search I did for one of my favorite artists, Eleanor Antin. Records will provide all of the information you will need to access the collections.