Having seen Photo Opportunities where multiple photos of popular tourist locations were layered together, and recalling a phycology test (like this) I did back when I was at University (there was good money for poor students partaking in Phyc tests!) I wondered about layering images of celebrities together to form some sort of average representation of them.
A wet Saturday morning of coding resulted in a Photoshop script that would allow you to mark the eyes in an image, then the script would scale, rotate and position the images into a stack, adjusting the opacity based on the total number of images.
It was then just a case of trawling Google Images (apologies to the copyright holders) to gather a series of celebrity images to process to see what came out at the other end.