ADC publishers has a large catalog of Tolkien books and represents some fine artists. Once a year they host exhibition of their represented artists in Moreton in Marsh in Cotswold, England. This exhibition (named differently each year) is announced each year on their ADC Promotions page.
To view a PDF file of the 2009 artists work, visit the catalog on line entitled Land of Enchantment. The artists are Ted Nasmith, Peter Pracownik, Ruth Lacon and Jef Murray. The art is well worth the wait for the download to finish.