I took part in the Muse Online Writers Conference in October, and D.S. Kane had a workshop on how to write about espionage realistically. The information I gained from that workshop will be helpful in some of the upcoming work, and I hope you'll find some of what I share will aid you, too.
Kane listed ten intelligence agencies in the United States: CIA, NSA,FBI, DIA, NCIS, ATF, DEA, NRO, ONI, U.S. Marshals. He said he knows of sixteen, even though he didn't list that many. One that he didn't know about, and that I do because of my research for my WIP, is the Air Force Office of Special Investigations (AFOSI), the Air Force equivalent to NCIS.
Of course other nations have their intelligence agencies, too, such as AFI (intelligence branch of the Israeli Air Force), The Mossad (Israel's "secret" service), and MI-6 (Great Britain).
The more one knows about the intelligence agencies used in writing fiction, the more believable the writing is. Research is vital. I would suggest to begin with D.S. Kane before going to some of the following works:
John Perkins, Confessions of an Economic Hit Man
John LeCarre, Tinker, Tailor, Soldier, Spy
Thomas Gordon, Gideon's Spies: The Secret History of the Mossad
Peter Wright, Spy Catcher: The Candid Autobiography of a Senior Intelligence Officer
Thank you, D.S. Kane, not only for an interesting workshop, but also for information to help writers be better writers.
Oh, yes, to register for the 2010 Muse Online Writers Conference, click on the title. Registering now means you'll receive all the notices and won't forget until after the deadline.