God knows why but its there. Main page link here
Edit and Update:
Enemybook is an antisocial utility that disconnects you
to the so-called friends around you.
Enemybook is a Facebook app that allows you to manage your enemies as well as your friends. With Enemybook you can add people as facebook enemies, specify why they are your enemies, notify your enemies, see who lists you as an enemy, and even become friends with the enemies of your enemies. Ever wanted to "enemy" somebody instead of friend them? Finally you can. This app remedies the one-sided perspective of Facebook.
Keep your friends close, and your enemies closer...