Same here for me actually.
I only have 61 "friends". Most of them, arround 22 or so, are my old classmates, and I only keep in touch maybe with 8 of them, and not that often anyway. 7 are my family members. I somehow have three people who are my sisters friends, I'm not really sure why they've added my or why I've accepted them... There're 8 former roommates, and I only keep in touch with 3 of them. 5 people with whom I've lectures together, though I only talk with two of them through facebook. And other people don't fit into any of those categories and I only talk with two out of them... so.... I could only leave 20 people among my 'friends'.

Though about the addiction, I don't think I'm addicted to it. Just like LittleForgetMeNot I go there when maybe I'm bored or so, just check on my family maybe or those couple of people I keep in touch with from my home country and stuff like that... But I never play any games there, though I do like to join groups and like stuff .

It is a bit usefull for me right now, when I'm away from home, though I do talk with my family through msn mostly (phone is a bit too expensive) but sometimes it's better through facebook... sometimes put a song there that we all now about and stuff like that. It's also nice to find out what my old classmates are doing in their lives and so on.
Though when I get back home it will be useful for me to keep facebook to check on people whom I met here where I'm studying, it's somehow easier than writing e-mails and most of them don't have msn, they use skype, but I don't use skype, so there's only facebook left for us .

I also joined pages of things and places I like and it's a lot easier to follow news about them through facebook than signing for newsletters from each of them.