Post Secret is a group confessional, where the site admin solicits deep, dark secrets from anyone that sends theirs in via postcard, then scans them in, and hijinks/hilarity/psychosis ensues. Kinda like grouphug, but more visual and has a bit of a barrier to entry.
SiegeSoft is a company that makes an anonymous web browser for surfing sites without getting any cookies, without recording your IP address, and without leaving a trace of where you went on your browser. I don't know how much use this would be (besides, say, looking at porn sites at work or something), but the most amazing part of this is the programming was done by 15-year old and 16-year old kids, who are now worth at least $750,000.
Has someone gotten you so mad you'd like to insult them? Are you the non-confrontational type? Well then, give Synge.com's Insulter a try. It's a totally anonymous way to get back at someone. Too bad U.S. Government officials don't like it...