The Farber Gravestone Collection is a collection of more than 13,500 photos of more than 9,000 gravestones in the northeastern United States.
From a genealogical perspective, this is not a huge number, but for the gravestone depicted it provides excellent black and white photos. There is also information about who carved the stones.
The gravestones are searchable by name.
This site is not like Find-a-Grave where the focus is the person buried, but rather who made the stone, and the artwork involved.
The url is http://www.davidrumsey.com/farber/