Reddit.com has a subsection called IAmA where people post threads stating something unusual about themselves and invite readers to "Ask Me Anything" (AMA). There are some interesting threads by a girl who survived a school shooting, a Daily Show intern, the saxophonist from the Saturday Night Live band, and others.
I posted a thread called IAmA Former Mormon Missionary AMA, not really expecting much to come of it. Much to my surprise, it got over 300 comments. I spent about 9 hours answering questions. Even more to my surprise, the vast majority of questions were civil, polite, and respectful. There was lots of good discussion on a lot of topics that don't often see the light of day.
Check it out at the link above and feel free to leave a question!