I got one of my best friends to watch it one night when we were bored on netflix. He seemed a little apprehensive (i put on the very very first episode of the series) because it was pretty girly, but half way through it he started asking a lot of questions and started sounding interested, especially when the first episode ends and its like a cliff-hanger when Nightmare Moon comebacks. He was like, "Dude, play the next episode i need to see what happens." and from then on he became a brony.
I also converted another one of my really good friends because my friend (from the story above) and i were watching it and he became hooked on the show almost immediately. My friend's neighbor (still the first one) thought him and i were weird for watching the show, but he gave it a try on his own time and became a huge brony. Those are pretty much the only people i've turned into bronies. I've gotten a few others to watch the show but they didn't become bronies, but they did like the show.