PostSecret is an ongoing community art project that allows people to share their secrets anonymously. People send in postcards with their secrets and Frank Warren, the site owner, posts a selection of them each week. More information about how it works can be found at the site.
The PostSecret blog has had over 50 MILLION visitors in the past two years and Frank has always maintained the site ad-free. He contends, and I agree, that by keeping it free of advertising it makes people want to open up and share. Ads would taint the image, making it appear like a commercial venture instead of the helpful outlet it truly is.
Frank has taken some of the postcards and created some wonderful books. He also teamed up with Amazon to help further offset the costs of running the site. For every purchase you make with this link, Amazon will donate 10% of the proceeds to the PostSecret Project. If you're going to be buying from Amazon anyway, please take a moment to do it with this link. It doesn't cost you anything and it helps continue a very worthwhile project.