If you think they'll stop at domain registrations, you've been smoking some of that stuff that the libertarians want to legalize. Sure, they might not now, but five years from now they'll decide that people who conceal their identities online are either perverts or terrorists.
Howard Dean and others wanted us to all have to ID ourselves online, so that anything we did could be tracked. Now, he maybe a crackpot, but there are many others like Joe Lieberman who hold positions of influence or power who would push something like this through.