Even with the very emotional parts of the evening, some of the funnier moments are produced when people bring a long their friends. That's where some of the best secrets come out, Warren said.
"I would encourage people to invite they're friends because they usually tell the best secrets," he said. "It's usually because the secrets involve the person who invited them. Then they can use them as blackmail."
Warren reads and keeps everyone of the postcards he receives. He said it has helped cultivate a greater appreciation for shared human nature, but said there can be a dark side to being privileged to read complete stranger's deepest secrets.
"I'm not shocked anymore but everyday I'm still surprised," he said of the postcards he reads. "It feels like a great privilege that over half a million people trust me with their greatest secret. But it can be burdensome reading painful secrets day after day."
He keeps an archive that he said will end up somewhere, but currently he puts them into exhibits that go across the country. Currently at UAlbany, the display he has is called "Life, Death and God", which he said contain some of the more funny, sexual and soulful secrets.
With people going to these events and being able to view these postcards on the web site, Warren said it shows them that there are others out there that are carrying a troubling secret.
"I hope it works to build greater empathy with people," he said.
When Warren started the project, it was as a submission to the Artomatic bi-annual arts festival in Washington D.C., his hometown, in 2004. He handed out 3,000 postcards to strangers on the sidewalk and began posting the results of the project on his web site. Once that happened, Warren said the project went viral overnight.