The ones I can think of are the FBI, ATF, and whatever section of homeland security happens to be awake that morning:

[T]oday’s Transom has a downright disturbing item about Brooklyn artist Chris Hackett ... who is constructing a fully-functional suitcase bomb. The piece is courtesy of the Madagascar Institute, a radical art organization which is organizing an exhibition to be shown at either Cooper Union or South Street Seaport the week of September 11.

The saddest part is, when the various local, state, and federal law enforcement agencies come and shut this down, they'll actually have the nerve to a) act surprised, b) claim censorship, and c) blame neoconservbushitlercans.