At this beautiful new site, Geocoded Art, landscape paintings are geocoded and can be searched with a map interface. Or you can look up a favorite work by artist or title, and find out where in the world it was painted. All works are in the public domain. This is already a rich database which hopefully will continue to grow. This will surely be a favorite for art-history courses, giving context to paintings. However the stated goal is also “to use fine art to illuminate geography”. Found this via Google Maps Mania.
Update 6/7/2018: Geocoded Art seems a bit neglected, but works. Google Maps Mania still going strong! Amazing mashups, so many to investigate. Wandered over to David Rumsey collection site. Must return soon.