Lauren= "Crowned with Laurel", a Greek symbol of Victory.
Marie= Well, it's just derived from Mary. How dull.
Anastasia= "She will rise again,"
My last name is derivative of Michael the arch-angel.
EDIT: "Sea of bitterness" is a speculated meaning. Others include "rebelliousness." After a bit of digging, I've found that Marie is, as I said, derived from Mary, and that Mary is most likely stemmed from the Egyptian word mry, meaning "beloved" or "love." So I'm terribly bitter, but it's not because of my middle name.