Okay, not strictly about books, but this is a fascinating blog, and there have been three books created out of the material collected by PostSecret.
PostSecret is an ongoing community art project where people mail in their secrets anonymously on one side of a homemade postcard.
Check out other people's secrets, or send one in, here:
From a post on the blog: "Every single person has at least one secret that would break your heart. If we could just remember this, I think there would be a lot more compassion and tolerance in the world."