Can a movie really define a generation? The Social Network comes damn close. It uses the tangled roots of Facebook, created by anti-social Harvard undergrad Mark Zuckerberg (Jesse Eisenberg) to show how technology is winning the battle against actual human contact, creating a nation of narcissists shaping their own reality like a Facebook page. If youth can't see itself in this movie, it's just not paying attention. Here are 12 other movies from the past half century that caught a generation in the act of defining itself.