Don't let this one fool you. On your initial visit this site looks daunting. This collection contains materials from hundreds of libraries around the the United States. It may not appear to have much for the genealogist. But, take a closer look and be creative with your searches. I did a search on the word "genealogy." The resulting listing showed hundreds of rare volumes of family history books including several volumes of "The New York genealogical and biographical record." I think you'll find yourself spending hours at this site. I know I plan to spend more time here.
Here's the link: