Just come across a really interesting interactive project from Estonian Professor, Tanel Tammet, called 'Sightsmap' which overlays a heatmap onto a Google map platform allowing users to pan and zoom around the globe to see the locations where the most intensely photographed areas in the world.

The heatmap is a representation of the number of available Panoramio photos for a given area. You can zoom into each location and then switch on the 'photo' view to see the images taken from each location. Furthermore, a drop down option lets you display markers for the most popular 5, 10, 100, etc. locations in the world.