In no way can I attempt to build a comprehensive bibliography of books on Viet Nam. I'm still reading so the list will never be complete. Here are, however, some titles that I feel do an excellent job.

The Warriors

Edelman, B (edit). Dear america: letters home from Vietnam. Norton, 1985.
Eilert, R. For self and country. Pocket Books. 1983. (Thanks Paul for loaning me this one, ever want it back? ;-)
Mangold. T. The tunnels of cu chi. Berkley Publishing Group. 1997.
Michel, M. The 11 days of christmas. Encounter Books, 2002.
Palmer, L. Shrapnel in the heart. Vintage, 1988.
Reed, P and Schwarz, T. Kontum Diary. Summit Books, 1996.
Santoli, A.To bear any burden. Ballantine Books. 1985
Santoli, A. Everything We Had. Random House. 1981.

There are some apparently good novels of the historical-fiction genere out there but I do not have the combat experience to honestly recommend them.

Docs and Nurses
Glasser, M. 365 Days, 1986 (Out of Print...see Amazon.com used)
VanDeVanter, L Home before morning. Beufort Books, 1983.(Out of Stock but available used at Amazon.com)

The POW/MIA Debate
Jensen-Stevenson, M and Stevenson, W. Kiss the boys goodbye. Plume Books, 1990.

View from the other side
Ninh, Bao. The sorrow of war. Riverhead Books, 1993.

One I cannot recommend:
Appy, Christian. Patriots: The Vietnam war remembered from all sides. Penguin USA, 2003
(Billed as a definitive compilation of stories from all sides of the war I found it heavily weighted with the voices of the North Vietnamese veterans and U.S. antiwar protesters. The stories of the South Vietnamese, Korean and Australians who fought and died there are seldom heard within its pages. Worth a read, but in my opinion heavily biased in its tone.)