I watch a show about this and thought people here might be interested in reading some of the essays on the website. Some of the essays are very interesting and others I've never thought of as being part of photography.
Smithsonian Click! Photography Initiativeclick! photography changes everything is a collection of original essays, stories and images—contributed by experts from a spectrum of professional worlds and members of the project’s online audience—that explore the many ways photography shapes our culture and our lives.
A couple of videos from the show I saw:
Smithsonian Spotlight: Click!