In a bit of Tom Sawyer-inspired app making, the New York Public Library has created an online application for rectifying their collection of digital maps of New York City. "Finding control points is so much fun! It is truly an honor to allow you, our special internet browser, to assist us in collecting them." The NYPL Map Rectifier allows you to export the rectified maps as KMLs. They've also added a separate section for maps of Haiti to assist in earthquake relief.