I have experienced just about every reaction I listed. When I told my family they were shocked, angry and upset. I grew up going to a very conservative baptist church. So,I knew that my mom would be shocked and sad, but I was surprised, to some degree, when she got angry. Excluding weddings and funerals, my dad only went to church when my sister and I were singing and even then we had to beg him to come. So, when I found out he was upset and even a bit angry with me I was flabbergasted. Looking back now I think he got angry because my mom and sister were so upset that they were making the house miserable for him. Also, he may have thought that I was going to become a criminal and that I was no longer going to visit them. With time, my family realized that my decision to become an atheist wasn't something that I was going to change just because they didn't like it and that this decision didn't make me a horrible person. Currently our relationship has returned to normal other than the fact that we don't discuss religion.
In stark comparison to the reaction I got from my parents a few of my friends actually laughed and congratulated me. There were a few friends that I felt the need to apologize to, because when I was a Christian teenager I had witnessed and invited them to church so many time that I am not sure why they were still my friends. They were gracious enough to forgive me and I am really glad that they never did become Christians.
Again, I would really like to hear your stories. If you haven't told anyone you are an atheist, but would like to leave a comment, share how you think those closest to you would react if you did tell them.