Noah Snavely's Phototourism system was featured on the main page of cnn.com for several days after the Obama inauguration, and I'd guess that tens of millions of people from all over the world tried it out (there are about 160000 pages *about* this on the Web). Here's one:

http://news.cs.washington.edu/2009/01/19/cnn-teams-with-photosynth-to-crowdsource-inauguration-coverage/