This is inspired by a question Regullus asked.
I've met a friend I made on the internet on several occasions, and we get along very well and have a good time together. He has had opportunities to meet numerous people in person that were originally internet aquaintances, and they have on the whole been pleasant encounters.
My other encounter with an internet friend was less pleasant, as he failed to recognize that I am happily married and was not interested in running away with him and starting my life over. He did also meet my husband, but just sort of... refused to acknowledge his existence. I no longer speak to this person.
Numerous meetings have gone on between various members of Planet Baldur's Gate, mostly Americans meeting other Americans and Europeans meeting other Europeans (due to financial constraints more than anything). On the whole, they have been successes. About 6 of our Dutch and Belgian members got together for a day last year, and I believe it was a dozen of the Americans who gathered in Las Vegas for a weekend in the fall. There is talk of doing a big meeting again.
I know PPG member meetings have occurred as well and look to have been enjoyable for all parties involved.
So, have you done it? Was it good for you? Would you do it again?
Also, if you are meeting someone you consider a friend, is that inherently more likely to be a successful venture than if you are meeting a potential romantic partner? It seems to me that it would be a lot less stressful.