Well, because I'm a sucker for this kind of thing, I've signed up to Friendster using [my surname]@email.com. I'm assuming that if you can demung that, you're most likely human and there's a reasonable chance you actually know me. So if you want to link to me, please feel free.
Like many such things, it's the kind of thing that only works well if lots of people, and lots of people you know, are in the system. I think I'd rather pimp it this way than send those annoying emails that effectively do the website's marketing for it.