Randy Seaver tackles the following question in his Digging For Answers column: What are the best online databases for cemeteries?
There are quite a few online databases for cemetery records. Some records are in large databases for completely surveyed cemeteries, and other databases have only partial compilations. Many of these records were generated by volunteers working with the cemeteries, or by just "walking the cemetery" and noting the inscriptions. In many cases, genealogical and historical societies have sponsored projects to collect inscriptions and/or cemetery burial records from cemetery files. Of course, there are many cemetery inscriptions and burial records that are not online.
For Randy’s list of online cemetery resources, read the entire article in the Graveyard Rabbits Online Journal.