Enemybook.info models itself after the age-old saying, “Keep your friends close, and your enemies closer.” The site was created as a “riposte to the perceived bogus nature of many online friendships.” Just as you might classify “friends” on Facebook, you can specify why certain people are your enemies and see who considers you an adversary.
Hatebook.com also might look similar to Facebook, but it takes a “less friendly approach” to online socializing. The site is an “open forum for abuse and aggression” that lets you befriend “other haters,” track enemies with an “Evil Map,” and stay posted on the activity of “Other fricking idiots.”
Snubster.com lets you build “personal lists of enemies” from your Facebook contacts. You send snubs to foes, informing them that they are either “On notice” or “Dead to me.”
Source: Financial Times