I heard "Memory of trees" by Enya at a friend's birthday party back when I was a child, and I knew I absolutely HAD to get it for myself. So I did, and the wonderful world of celtic music was opened to me.
Fast forward some ten years, and someone got me to listen to a song by Nightwish, from the album Wishmaster. Then another one. Then the whole thing.
That album hit naive silly me, who thought all metal was hairy guys puking into microphones and using their instruments like they were trying to hit people with them, like a freight train. My music tastes evolved overnight, and from that day I've been meticulously collecting (digitally) every female-fronted gothic/melodic metal album that I can lay my hands on.