Living Small-Manhattan

I found this great Daring Downsized article on PointClickHome.com. The whole apartment made me fall in love with small places all over again and also made me think I shouldn't have been so quick to dismiss that 415sqft condo in the OC. Many New Yorkers would kill for that much space. Well here are some pictures of the 550-square-foot run-down co-op redo. What is the smallest square footage you think you could live in?