I was told once that things I said in english class helped convert a friend of mine to atheism, but this was so long ago that I can't really remember what I said. In terms of my own experiences of giving up beliefs I've had, a key factor is readability and honesty in presentation. Things like Yvain's non-libertarian faq are fun to read and seriously strive to address the viewpoints that I formerly held as a libertarian. It didn't make fun of libertarianism, but allowed it to reveal its own silliness by talking about it.