Hello,
There are several common names where I come from, like María or Ana for women and Pedro, Juan or Manuel for men.
My family name, Veira, is not very common, but it tells everyone very often that I'm from the north west of Spain. I've never searched the net to find more people - besides my family - with this family name, but I remember once years ago when someone from the United States tried to make contact with the Veira people in Galicia, because he was trying to get in touch with every Veira he could find in the world. It didn't worked that time, maybe next.
Besides all this, I don't like to call people by his family name, it reminds me of the primary school, where everyone called the other that way. I think we have a first name for some reason, and I almost ever use a surname to talk to someone.
What's more, I think that in Spain, when you meet someone for the first time is the other one who tells you how to call him or her, because many people prefer his or her nickname instead of his first name, and they say so.
Anyway, in Spain there are a lot of family names that come from a older first name. In the Middle Age this was used to tell everyone that one particular person was the child of someone. For example: Sanchez, son of Sancho; Rodríguez, son of Rodrigo...and so on. And this family names have reached nowadays as common Spanish ones, as now whe actually have two family names (our father's and our mother's) besides our first name.
Marta