"Explore museums from around the world, discover and view hundreds of artworks at incredible zoom levels, and even create and share your own collection of masterpieces. ... Simply select a museum from the homepage and then either chose ‘Explore the museum’ or ‘View Artwork’. Once you are in the main site use the drop-down menus or the side info bar to navigate between artworks and museums. Finally create and share your own collections online." (quoted from their website)
The images used to introduce galleries participating Google Art Project are stunning.
Links for Facebook viewers: my art collage in Vuvox; video about the project)
P.S. I'd forgotten how quick it is to build a collage in Vuvox if you don't get fancy -- but the creative possibilities are a lot of fun.