Bluemoon Interactive, a small codeshop, maps touristiness, based on uploads to Panoramio, a site where people share photos of their favorite places. Yellow indicates high touristiness, red is medium touristiness, and blue is low touristiness.
Europe is much brighter than the rest of the world. The coasts of the US has got some brightness, along with Japan and some of the coasts of South America.
The question is are we really seeing levels of tourism, or are we looking at who uses Panoramio? I'm inclined to say the latter, simply because all of Europe is so crazy bright.