Flickr user Neil Kandalgaonkar aka brevity has created a script to average photos in the manner of artist Jason Salavon. Cool stuff.

Some links:

Brevity
Eiffel Tower
Photographer's Own Shadows
The Seasons
Salvon
Every Playboy Centerfold from the 1970's
Top Grossing Film of All Time
Class of 1967 vs 1988