1) UFOs and the National Security State, vol 1 & 2 (and some day 3), by Richard Dolan
2) The Hunt for Zero Point, by Nick Cook
3) The Missing Times, by Terry Hansen
4) Alien Agenda, by Jim Marrs
5) Above Top Secret, by Timothy Good -- also, I have a feeling that Tim’s new book Unearthly Disclosure might also make the list. Hope to read it soon.
6) Strange Company by Keith Chester
I know that I am forgetting some, but those are a really great starting point for anyone who is interested in Ufology.