America
National Gallery of Art
National Museum of American Art and Photography
Metropolitan Museum of Art New York
Smithsonian Institution
National Museum of American History
American Museum of Photography

Northern California
Fine Arts Museums of San Francisco De Young and Legion of Honor
Berkeley Art Museum and Pacific Film Archive
Exploratorium San Francisco
Museum of the City of San Francisco
Tech Museum of Innovation San Jose. With monthly "Tech 10" winners
Cantor Center for Visual Arts and Rodin Sculpture Garden
Crocker Art Museum Sacramento

Southern California
Los Angeles County Museum of Art
The Huntington Library, Art Collections, & Botanical Gardens Pasadena

Europe
Paris Pages: Museums
24 Hour Museum museums of the UK
National Gallery London
Tate Modern London
Rijksmuseum Amsterdam
Musee Rodin
Prado Madrid

Germany, Austria, Switzerland
Museumlandschaft "die Museen im deutschen Sprachraum"
Deutsches Historisches Museum Berlin. With links to other museums and memorials, most in Germany.
Staatliche Museen zu Berlin Stiftung Preußischer Kulturbesitz
Haus der Geschichte der BRD Bonn
Museen in der Schweiz Museums in Switzerland
Neanderthal Museum Mettmann
Deutsches Museum Naturwissenschaft und Technik, München
Museum für Industriekultur des Ruhrgebiets
documenta Kassel