I was curious when I came across Snapmania's Tourist Remover. I thought now how on earth can they guess what is behind the tourist and fill it in.
The system actually relies upon you having several (for a better result) photos of the same place. This way it takes the photos and uses each to patch together a final photo without the unwanted tourists walking by like here when you could be taking a picture of a Ferrari :
Or like this :
And after using the Tourist Remover Service, voilà , your final photo without a single tourist in site :