World of Warcraft, almost 9 years ago. We were in the same raiding guild, and tended to talk a lot of crap about the raid leader (he was an abusive prick), and some of the less awesome members of the raid.
We ended up becoming pretty good friends; he had no idea I was a girl because I never really spoke in Ventrilo (and, according to him, girls aren't usually that good at video games haha). Maybe 6 months into the friendship, our guild website had a 'post your picture' thread. I was somewhat mortified that this person I had been speaking to was a very attractive guy - I kept thinking, oh god, what kind of dumbass things have I been saying to this guy. As soon as we both realized there was potentially a physical attraction component to the relationship, we got even closer.
At the time, I was living in Texas and he was living in Florida. After a couple months of the conversations being a bit more sexual and serious, we decided to finally meet. I have never been so nervous or exhilarated about anything in my entire life. When I saw him for the first time, I felt like my heart was going to explode out of my chest. Things were a little awkward for the first 10 minutes or so, but we fell right into a comfortable rhythm quickly. Certainly it wasn't love at first sight, given how well we already knew each other, but I have never felt that depth or degree of attraction towards someone.
Flash forward one month, and we decided to meet again, this time in Alabama (roughly halfway for both of us). At the end of the weekend, I said I couldn't do the distance thing anymore. He drove back with me to Texas, I packed up all of my stuff, quit my job, and we drove back to Alabama, he got in his car, and I moved in with him right away.
I was 22, and he was 20. It all the makings to not work. I expected it not to, but it felt so good I thought I would ride it out until it ended. We've had our ups and downs over the years, we even briefly broke up for a while, but in the end I always came back to him. We recently got engaged, and will get married sometime in the next few years.
The whole thing was just insane, it shouldn't have worked, but I don't regret any of it.