The concept is simple. Ask people to write their secrets on a postcard anonymously and mail it in. Publish the cards on a website called Postsecrets.

The response was phenomenal. So much that a few books were released.

This is the most authentic book I've ever read. The secrets are written on collages artfully designed. The book is an art form by itself. This is highly recommended. Just read the positive response from hundreds of reviewers on amazon.com.

Read more about Postsecret's history on wikipedia.