I signed up for a Facebook account in college at the behest of a girlfriend, never updated it, left it sitting around for about 3 or 4 years and then pulled the plug on it.
I never really saw the point, since I don't find it difficult keeping up with my friends the old fashioned ways (talking to them on the telephone in realtime, emailing them, and socializing with them). The only things that Facebook seems to offer that those things don't are 1.) being able to look at album after album of photos of my friends in bars, and 2.) being able to look at lists of my friends' favorite movies at any hour of the day or night, neither of which I really need to do.