I just found a great resource called the Real Estate Record (and later the Real Estate Record and Builders' Guide) that has been put on line by Columbia University. http://ldpd.lamp.columbia.edu/rerecord/browse.php and to search http://ldpd.lamp.columbia.edu/rerecord/search.php However, I initially found it with simple google searches. I would never have thought of using this for genealogical research, but what it did was tell me whether people were alive or dead at certain times. The vital records index is great, but if you have a more common name, like Mary or Sarah Brady, how can you be sure (without ordering every death certificate or going to the Municipal Archives) if that woman is yours. I had found possible death dates for these women in Manhattan, but could not be sure they were alive after the 1880 census. Googling their sister Amelia, who I knew lived until 1925, I found their three names in this source when they sold their house at 144 127th St. April 21, 1890. Now I could be sure they lived until 1890, making it more likely that the very old women who died in the next decade were they. Charmed with my success, I googled their married sister, Ann Eliza Prophet, and found her named children selling a store and tenement on 126th St (their father had been a grocer). In one of two notices they were called "heirs Ann E. Prophet." Aug 30, 1890. Therefore I knew she had died by then. I am sure you all can come up with even more imaginative ways to use this. Elizabeth W. Knowlton