On the one hand, they make faith and morals central to the process of matching.
You must take the initiative in attending to those whose faith and morals seem compatible.
First, they provide a large pool of potential matches and they all have a large number of Catholics present on them.
Second, they all have ways of indicating how important your faith is to you and matching you with people based on this characteristic.
And nostalgia is a potent force on the internet, as Facebook itself has acknowledged with its memory-focused Timeline.
Of course the real test will be whether Friends Reunited picks up its membership from the 1.5 million that currently visit the site.