Snubster, oddly enough, smushes itself into Facebook. How cunning, eh? One slightly scary element is the "email the person you are snubbing" feature. Apparently you can "put them on notice" to let them know they are pissing you off and they will adjust the behavior. If they don't, Snubster also has a "Dead to Me" list. Not sure who they email in that case. Perhaps saintpeter@heaven.org and he will be sure to deliver it.
Snubster Stickers
IMolatr - the tab on the upper right that says, "go away" is a nice touch. Be sure to click the Sign Up button.
Hatebook proports itself to be "an anti-social utility that disconnects you from the things YOU HATE." The default first friend is amusingly, Dr. Evil. Much cooler than "Tom".
Enemybook bills itself are "an anti-social utility that disconnects you to the so-called friends around you." Probably one of the more inflamatory aspects of Enemybook is the SuperFlipOff! mashup to Facebook.
More interesting is a blog posting entitled, Forced Virility and the Degeneration of Social Networks.