They can watch you pick your nose on the street in real time. They know when you are home from your water and gas usage. Every time you use a bank or credit card, they know what you bought, in real time. They keep dossiers of what amounts to vicious gossip on people, and their resources are mostly being used by local police doing investigations of street crime.
They haven't prevented a single real terrorist.
The couple attacks that did happen since the establishment of the fusion centers were lone wolves. One guy lost his job and couldn't pay his mortgage, and the other one was just insane. Otherwise, I don't think there's any real terrorists out there, save the ones on government payrolls. Oh, there was that group of anarchist idiots who were going to try and blow up a bridge in Ohio, but they were both very incompetent and totally agent-provoked. Without the FBI offering them fake explosives, I think all they would have done is go to protests.
This continual branding of Liberty movement people as "terrorists", the claim that the Tea Party is like Al-Qaeda, is all ridiculous, politically motivated bullshit. I cannot think of a group of people more law abiding and well-wishing of our country, Constitution, and Bill of Rights than the Liberty movement and the Tea Party. But the tactics of the current administration are, shall, we say, less than honorable. It all reminds me of stories of Communism, and the Stasi.
Interestingly enough, the former head of the Stasi, Markus Wolf, was brought here in 2003 to head up DHS. And if you don't believe Prison Planet's link, here is another.