It's interesting, I have the same few spots as well. Dont' make it back often as I should (installed Adium to help with this), but it's interesting to see where we all met as teenagers, now talking about other things that have happened, whether it's marriage, family, business, etc.
The uncompromising and unquestioned loyalty that exists from having a buddy in another city is something social media (and maybe even dating sites) could learn a thing or ten from.
I'd say online message boards (phpbb, etc) in from 99 to 2007 or so were similar networks. There is something about semi long form communication that can't be liked, tweeted, shared, etc to be improved.