Air Force Link: U.S. POW/MIA official cites breakthrough in Vietnam [ 19. March 2005, 05:59 AM: Message edited by: Deep Web Diver ]
Try http://lcweb2.loc.gov/pow/powhome.html and http://www.abmc.gov/abmc47.htm . This last one is the American Battlefield Monument Commission site. No database with names, but they are able to help if you want a picture of a name on the Honolulu memorial were the 2000+ MIA's are mentioned by name.
I read something about this in the New Yorker. Apparently the acidity of the Vietnamese soil means that stuff decays really quickly, making the job even harder. It's also sort of creepy to think that in a lot of modern wars, "Missing in Action" just means "couldn't find the various body parts". Think of all the men in WWI who were MIA after getting blown to bits by a shell or drowning in a crater full of mud.
Expect this role to take forever, they are still finding lost aircraft in Papua-New Guinea 60 years down the road. Many of these are found relativly close to points of civilization, it doesnt take long for the jungle to reclaim its territory.