Despite the fact that about anyone I know has a Facebook account, I'm getting along just fine without.
I do have an account at some other, similar website, but I haven't really been there for years and never really saw the appeal of these kind of websites anyway. If I want to keep in touch with friends, I'd much rather just hang out with them IRL or call them or send them an e-mail if I really need to speak to them quickly. I especially don't see the point in having hundreds of "friends" who are basically people I've met only once in my life and I don't really care one tiny bit about anyway.
Furthermore, I just feel that the "keeping in touch" that you do on social network sites is very shallow.