Age of Empires started my interest in history. It never dethroned my love of physics, but to this day, history is a subject I enjoy.
While I didn't meet him in-game, I met one of my friends because of EVE Online. I heard that he played, so I went to his room and introduced myself. We soon discovered other common interests (video games in general, science fiction), and we're in the same department at college. Now he and another EVE-playing friend of his will be rooming together next year.
While I wouldn't say that I learned the value of teamwork from video games, they have certainly reinforced the concept. My most memorable experience was in Earth & Beyond. There was a haywire drone in the noob system that kept killing me. I joined up with two other players to kill it. But we went at it haphazardly, and we lost. After we got recovered, we went at it again, this time in formation. We won.