I recently created a LinkedIn account and proceeded to add people from various parts of my profession: past and present co-workers, and people I've "met" on the web (in quotes because I haven't met most of them in person).
On a lark, I looked up my alma mater and thought I recognized some of the names. Indeed, one person turned out to be an old crony, who also happens to be living in Souther California. After a couple of "are you who I think you are" emails, we got together for lunch this last Saturday.
I had a grand time. We ate lunch and spent the next three hours over coffee catching up. It turns out that we had many shared experiences (not all of which were happy ones). It was positively therapeutic: a few times as I was telling him about what I had done, I had to really stop and think, "Why did I do that? What was going thru my mind?" Unfortunately, we live at opposite ends of Southern California, so we won't be able to get together very often, but I'm looking forward to the next time we do.
So I guess I'm not as negative about social networking sites as I used to be. They can work, and lead to happy results.