http://www.pureonline.com/ (porn-masturbation addict site)
http://www.obscenitycrimes.org/
http://brownback.senate.gov/
http://www.moralityinmedia.org/
http://www.fcc.gov/
They're more all enemies of freedom of expression, etc...., than enemies of porn though.
I should think those were obvious but it never hurts to post them up; and have them handy whenever idiotic decisions are made at the government level to flood these things with offended emails.
And here's a site that helps:
http://www.peacefire.org/ - explains how this porn-blocking software is basically stupid censorship and how to circumvent it.
Porn is not a target for the Brownbacks and Bushes; it's a means to an end, just the most obvious means (actually since the patriot act it's the second most obvious; terrorists in your toaster is #1 now).