So far I haven't joined it, let alone used it, despite all the "xyz invited you to join Facebook" e-mails I've received over time. I set up a profile on Windows Live and tried out CDFreaks' social networking features (mostly removed in MyCE), but abandoned them now. I never joined any others such as Bebo, MySpace, Twitter, etc., let alone feel left out by not joining any.
Personally, I find the best ways to keep in touch are e-mail and Telephone. If your friends are local, why not meet up now and again? When I was at 2nd level school, another popular way friends kept in touch before social networking websites and mobiles was by CB radio! For realtime chatting and Video, there's also MSN (Windows Live) messenger and Skype. For sharing photos, I either send them by e-mail or directly via MSN, as this way I know who receives them.
Do you really need to put your personal details, photos, etc. in public for 1,000's of strangers to look at?