A number of the links posted by lrd are inactive.
Here is a good one I like to use at the AWC which links to a good group of lists of interest to many here.
http://www.carlisle.army.mil/library/RecReadList09.pdf
For the more tactically oriented, the CGSC also has some good list links.
http://www-cgsc.army.mil/carl/gatewa...ding_lists.asp
When considering using lists like these, one must be careful of who the list maker might be and why they made such a list. For example, a list like the Vietnam one has some issues as far as I'm concerned - e.g., it is missing
America's Longest War: The United States and Vietnam, 1950-1975by George C Herring (perhaps the single best overview of that war)

and includes
Bloods 
which - without qualification by the list maker of its contents - has been proven to contain some of the most outrageous falsehoods ever perpetuated about Vietnam veterans and SF.
Caveat emptor and GIGO applies as equally to one's reading selections, too.
Richard's $.02