Antisocial networking sites, created in the backlash to the popular social networking sites like Myspace and Friendster, allow you to create lists of people who you don’t want to be friends with.
Snubster lets you create a list of people that you don’t want to be friends with. Simply enter a person’s email address and they’ll get a message to says they are “dead to you”, or “on notice” along with a reason, if you see fit to give them one.
Other antisocial networking sites include isolatr and introvertster.
(Via New Scientist Technology Blog)