I remember reading the book "Strega Nona" as a child, about a wonderful old woman who helps others. (Apparently "strega" means witch in Italian and "nona" is grandma.) I would love this name if it weren't for the "grandma" thing, and the fact that I think about Strega Nona whenever I hear it. It's so much better than Nina, which sounds whiney and nasal to me, and just as nice as Mona. Has a certain sex appeal too, a là Lola - no? Would be appropriate for a girl born on the ninth day of the month, or if the number nine was significant in some other way.
About the history of the name: It was the name of St. Nicholas' mother (the 3rd century AD) and in the same way, belongs to St. Gregory's mother. Both women were very devoted to Jesus-The Son of God.