I've been going line by line thru some cemetery books, I do that occasionally looking for people I have missed and dates that I do not have. Its a great thing to do especially if a family in a given location has a fondness for a certain cemetery, sometime going thru yields children born between census or possible older ancestors.
Once you have names & dates you can try to locate obits & death records to prove or disprove relationships. Of all the contributions that genealogy & historical societies make, I think the cemetery readings are one of the most important.
I have found so many leads and so much information by using the cemetery readings that many of the societies have done. I've also found maiden names in these books.
Beware of the annotations that sometimes come along with the books, without knowing the source of the information that they are including, taking the information with following up with your own research isn't the smartest thing to be doing. Keeping in mind that humans do make mistakes, either in reading the stones or in transcribing records, follow up on the things you find in the books. I have a tendancy to use the books where stones have been recorded in order appearing in the cemetery rather than alphabetically. I like to see who is resting next door. Never know who you'll find.
Having cemetery readings for cemeteries where your ancestors rest? Its a very good thing!