Thanks to Matt for telling me about Art Project from Google! While there is nothing like seeing art in person, this is a pretty great tool. Google partnered with many of the world's top museums (Tate Britain, MOMA, the Met, the Uffizi Gallery, Rijksmuseum, etc.) and uses streetview to simulate walking through their galleries. They also have high-res images from their collections that you can view up close (really, really close).