The Google Art Project combines the collections of over 150 art institutions, across 40 countries, into one massive online exhibit, powered by Google of course. As they state in the description:
Few people will ever be lucky enough to be able to visit every museum or see every work of art they’re interested in but now many more can enjoy over 30 000 works of art from sculpture to architecture and drawings and explore over 150 collections from 40 countries, all in one place. We’re also lucky at Google to have the technology to make this kind of project a reality.
Unlike many virtual counterparts to real-world exhibits, the level of detail is amazing. One can zoom in to see brush strokes created by masters hundreds of years ago.