If you are going on vacation to New York, London, San Francisco, Paris, Madrid, Venice, Rome, Amsterdam, Chicago, or any nice city in the coming months, these maps will tell you where are the most popular photo spots.
Flickr user Eric Fisher created these maps using the GPS information of images in Flickr, combined with the home city of the user taking the photo. The red spots show the most popular photo subjects, where every tourist goes "oooh" and "aaah", snapping images which will serve to torture family and friends back at home. The blue spots show normal photos, taken by locals, while the yellow ones are undetermined.
Accidentally, the maps allow locals to avoid the tourists. That's not very useful, however, as every local already knows how to do this without a map.