At St. Columcille's/Dean Brian McGuirc Church, they have an outdoor mass once a year, in August. I happened to be there at that time and was able to meet relatives I may never have met because of it.
With all the religious conflict in No. Ireland, you would think everyone goes to church regularly. Perhaps this is so with the older folks, but the younger to middle-aged, I found, were not such diehards. This mass was only about an hour, with people casually dressed, lounging on the graves of loved ones listening to the mass through loud speakers set up especially for the occassion. Thus, if anyone was ever going to attend mass, even just once a year, this was it, and I caught them while they were there. I scored lots of family photos and met most of them.
Aside from that, the mass was a lovely way to spend the afternoon and I believe lots of other towns have instigated something similar. It would be an easy inquiry, as this seemed to be a well-known event. The concept began as a way to get people to start cleaning up the graves of their deceased family members - and it worked, at least in Carrickmore.
From what I am told, the church cemetery there, in Carrickmore, where I attended services, used to be very rundown with no regard for public upkeep. After family members put someone in a grave, in effect, they said, "See ya!" Now, the place is absolutely beautiful - a perfect spot to sit and admire the view surrounded by the spirit of those so obviously loved and well cared for.