I've met people on GC that I know call friends myself. We have exchanged phone numbers and talk regularly on the phone. I have also met one when I was in Miami on vacation. There is one that I chat with in my own city that we have yet to meet. But we will put an end to that soon.
They know my name as I know theirs, and I know what they do for a livinging, as they know what I do. Once you get beyond just chatting on a GC forum, I think that people can and do establish friendships via the net.
Also coming to different forums, you may run into someone that you know. I found a friend of mine from college on this board that I had not spoken to in years. They had moved from the area, and now we converse all the time.