grouphug.us is devoted to recording anonymous confessions. It feels icky and uplifting all at once. Uplifting in that people can let it out. But icky too.
Anonymous confessions are entered via a form on the site. There are rules and the confessions are moderated before being posted on the site. To quote from the rules:
the type of confession that will nearly always be included is the type where you simply place your cursor in the little box and type a note about a fault of your own, something you did or thought about and are not proud of.
Via iamcal.com.