the Washington Post had a fantastic series which tried to get a handle on the complexity of the intelligence services operating in America today: http://projects.washingtonpost.com/top-secret-america/articl...

here's the leader:

The top-secret world the government created in response to the terrorist attacks of Sept. 11, 2001, has become so large, so unwieldy and so secretive that no one knows how much money it costs, how many people it employs, how many programs exist within it or exactly how many agencies do the same work.

It's a harrowing read.