The Inside Out Project is an ongoing global art project in which more than 100,000 people have created public art using portrait photos of themselves and their neighbors (video). Participants submit portrait photos to the Inside Out Project site. The photos are printed as large scale posters and then mailed back to the participants for public display.
The Inside Out Project was created by street artist JR. He won the 2011 TED Prize for the concept and launched the project in March of 2011. JR talks about year one of the project in this recent TED Talk:
photos via Inside Out Project