So, in my quest for all things metal and Tolkien I came across a few prog rock, and so :
Camel : Nimrodel / The Procession / The White Rider (1974)
Rush : Rivendell (1975)
Avalon : Land of Mordor (1977)
Archangel - The Akallabeth
Ainur, three Silmarillion inspired albums : From Ancient Times (2006), Children of Hurin (2007) & Lay of Leithian(2009)
Edit :
Ups, forgot to put this http://www.tolkien-music.com/ here after Kinja the post the first time..