OldFriends is the New Zealand version of the incredibly popular Classmates.com, and both of them offer the ability to reconnect with old school friends, or acquaintances, or crushes, or whatever.
When I first discovered OldFriends quite a few years ago, it was so exciting. I was able to reconnect with people! But after a few emails and promising to "keep in touch" with people - nothing. We all get busy, and there's usually no compelling reason to keep in touch, unless you work in the same industry or have friends in common.
That's why Facebook is so cool. While editing my profile, I added my high school (Avondale College 1993, FYI) and discovered I could search for others in the same year. Because I didn't go to uni I lost touch with a lot of folks from school, so it was really cool to get in touch with people.
So I've already had one person accept my friend request, and it's so cool to know I don't have to come up with a big long email message about how has life been since school, etc, etc... we'll get to know each other again just by being on Facebook.
There's something in that about how our concepts of social-ness (sociality?) are changing. But I don't know what that something is right now.