Marketing campaigns for dead artists are nothing new—think of all the hoopla for those long-gone French impressionists. But the meteoric posthumous rise of local photographer Vivian Maier, fueled by an intriguing discovery story and the power of the Internet, is unprecedented. Maier died impoverished and unknown in April 2009. Six months later, local real estate agent John Maloof—who'd previously bought a box containing 30,000 Maier negatives for $400 at an auction—posted a few of the pictures on the Flickr forum Hardcore Street Photography. Maloof also contacted some museums and journalists, and the rest is history: scads of media coverage, dozens of exhibits, four books (plus two more coming out), and two feature-length documentary films, all mining the story of Maier's life as an eccentric North Shore nanny with an obsessive and secret talent. Five years after her death, the starting price for a single print made from those undeveloped negatives is $2,200.