You can count on Bear Family to do a thorough job, and so they've released a thirteen (13!) disc box set with 334 songs (and a 304 page book) about the Vietnam experience, in soul and other Americana genres: "… Next Stop Is Vietnam - The War On Record: 1962-2008" v/a (2010). Earlier on, Kent had released the "A Soldier's Sad Story - Vietnam Through The Eyes Of Black America 1966-1973" (2004) and "Does Anybody Know I'm Here? Vietnam Through The Eyes Of Black America 1962-1972" (2005) v/a compilations, while Rounder had already released "In Country - Folk Songs Of Americans In The Vietnam War" (1991) … More on the subject via the links below … and for another angle, see Trikont's "Ho! Roady Music From Vietnam 2000" v/a comp and this link? (As for the Vietnam war on film, see here.)
http://en.wikipedia.org/wiki/List_of_songs_about_the_Vietnam_War
http://faculty.buffalostate.edu/fishlm/folksongs/americansongs.htm
http://www.npr.org/templates/story/story.php?storyId=3266035
http://www.k-state.edu/english/nelp/vietnam_music.html
http://www.brownielocks.com/sixtieswarsongs.html
http://www.jwsrockgarden.com/jw02vvaw.htm
http://vietnamwarmusicguide.com/
http://www.vietwarsongs.com/
http://www.battlenotes.com/

+ for info on this Withers gem: http://uzine.posterous.com/harlem-77