Listening examples as well as a story of one of his pieces that auctioned for $3.5 Million
http://lfa.atu.edu/music/barber/intro/beethoven.htm
http://www.npr.org/templates/story/story.php?storyId=4230263
Mozart
http://www.stringsinthemountains.org/m2m/1once.htm
Composers (Data and Lists of their works)