I've seen two, and the second one is the one that converted me.
The first was about 2 years ago. I was in the hospital and walking down the corridor and happened to look in a room a couple down from mine. My eyes about bugged out of my head when I saw this lady sitting up on her bed, and a large plume of what I thought was smoke billowing up above her head. She smiled and invited me in and proceeded to show me the first e-cig I'd ever seen (or even heard of).
The second was when I went to see my Pulmonologist for the first time. I was sitting in his office and his technician came in, exhaling this plume of "smoke". The shock must have been all over my face because he immediately said - it's vapor.
He then proceeded to tell me all about his e-cig (a 510 model) and where he got it, how much it was, how it worked. He then stuck a nice clean cart on the end of it and asked me if I wanted to give it a try. I did. I liked!!! I ordered my own 510 from the website he recommended and I've been vaping ever since.
It still tickles me to this day that I was in a doctors OFFICE watching this guy vape. But not just any doctor, a Pulmonary specialist - a lung doctor! And then I read all these news stories about how people are trying to get e-cigs banned. But I guess this particular doctor was a bit biased - the same technician of his that converted me, had also converted the doctor's wife, and probably saved her life in doing so. I definitely give him credit for saving mine. I never pointed out to the doctor that it was his technician that saved my life (and bettered my health) and not the doctor himself - hehe, I think I'll keep that irony to myself.