I've been following Post Secret for a while now. It's a site where people send in a post card with a secret they haven't told, or haven't built up the courage to tell. Some are really beautiful. Some are really depressing and/or scary. Most of the authors make me want to give them a hug and tell them life can be better. Then there are those who make these up just for shock value. You hope, at least I do, that some of the worst, scariest, heartbreakingly sad ones fit that category. You just never know. As a voyeur you get to decide which category they fit. You also get to share the emotion or sit as judge, which ever you desire.
The site act as a type of anonymous therapy. The idea that you have something you NEED to say, but can't. Express it extravagantly or simple, just get it out there so you're not the only one holding onto it. I think there is a lot of power in catharsis of any size. This small release of pent up anger/fear/jealousy/disdain/piety/pride/shame/longing/loss/love can have a positive healing affect. It may also be the catalyst for the card's creator to face their challenge.
Depending on your reaction or shared experience it can be therapeutic for you as the viewer as well. Here are some examples for you to begin your own exploration. If you haven't checked out the site or seen their compilation books, they are worth a look if not simply for their artistic value.
I have thought about making my own on occasion, but I tend to steer from public sharing of deep rooted secrets even with anonymity as a shield. Hell, I have a blog, I don't have very many secrets that aren't public worthy anyway. The ones that are, make me who I am and I'm not sure if anyone would gain anything from them should I put them in the world.