Superman and Batman (1977)

Growing up Heroes is a fascinating tumblr blog by Belgian comic book fan Franz Donovan, where people submit their old childhood photos of themselves dressed up as superheroes. From Wired's Underwire Blog:

Donovan pictures his online scrapbook as an exercise in nostalgia. “Growing Up Heroes brings back vivid memories of our own attempts to be heroes when we were uncomplicated, over-imaginative, nerdy kids,” he said.

The only things lacking are the "after" photos of these people all grown up: Link - via The Zeray Gazette