The Museum of Contemporary Art in Denver, U.S.A. has not only a great building, but also a great website design. Building made by Adjaye Associates.
Via Arch Daily
El Museo del Bario in New York welcomes visitors of all backgrounds to discover the artistic landscape of the Latino, Caribbean, and Latin American cultures. Their richness is represented in its wide-ranging collections and exhibitions, complemented by film, literary, visual and performing arts series, cultural celebrations, and educational programs.
They have a great website design, that is not only functional, but successful in using colors to represent the cultural diversity of latin america.