There could be some great battles fought if this were to happen.
In theory, if a couple of users banded together and recruited people in secret they could easily send a HUGE spam wave across the site. Getting back on topic, this could be caused from people wanting to be blocked as much as possible.
Dan will assign more moderators when he feels they are needed, and it could cause a lot of fighting, it may at first start out as friendly competition, but it would soon be just a bunch of people fighting each other, this would pretty much like Coheed said, cause war, and that is a lot more than AG can handle =P
Enemies list? Are we at war here?! This is a a website of peace, not a battlefield from heck! More nice way would, like everyone said, an ignore list and make sure you can only see it so you don't anger a member of the site. Maybe mods should have a mute power so you can have the user not being able to use forums for a time period. More peaceful way