In November 2004, Frank Warren gave out 3,000 self-addressed postcards randomly to people on buses, in art galeries, in between library books, and so on, inviting them to send him their secrets. The cards he received initially formed the basis for an art exhibition, but when cards kept coming long after he had stopped handing out postcards, Frank decided to post a weekly selection of about 20 secrets on his blog at PostSecret.com, out of a total 1,000 received every week (as he explains in an online video interview). Some of the secrets shared by people are funny, others sad, others still bordering on the obscene perhaps, but all without exception are interesting. Even if by now, due to extensive media coverage of the blog, perhaps not all submitted secrets are real, they may still ring true to other people reading them, and recognizing in them something relating to their own lives.
Recently the idea was taken up by the Dutch language newspapers NRC and De Standaard, who invite people to submit their (paper or electronic) postcards with secrets to www.briefgeheimen.nl. Whereas on PostSecret.com you can only see the weekly selection, Briefgeheimen.nl does keep an archive which is well worth browsing through.
A different but related initiative in Dutch is Gedachtenbordeel.be ('thought brothel'), where in exchange for a random thought you submit, someone else's equally random thought is returned. The name of the site refers to Peter Verhelst's novel Tongkat, subtitled 'Een verhalenbordeel'.