Here's something a trifle disturbing. The Mannahatta Project, which is trying to determine just what the island of Manhattan looked like when Henry Hudson arrived here 400 years ago, has figured out an ingenious way of raising money. For a mere $25, you can restore any city block to its presumed pre-urban pristineness - all that's left, if someone clicks on it, is your name. Above is the region east of Madison Square Garden - the green rectangles are blocks leveled by donors. The website's already done the same for Manhattan within the larger NY/New Jersey area. (The coastlines of the Hudson and East Rivers have been scrubbed, too.)
