SoundclickSince it is a dot com site, not strictly non-commercial. Does offer full mp3 access to artist repertoire.
Acoustic
Acoustic Guitar, Folk, Piano, Guitar, Rock, Vocals
Beats/Instrumentals
HipHop and Electronica Beats and Loops...
Classical
Mozart and Schubert, Chamber Music, Symphonic, Choral...
Country
Alternative Country, Christian, Bluegrass, Country Rock...
Hip Hop
Freestyle, New School, Spoken Word, Battles/Disses
Latin
Flamenco, Merengue, Cuban, Pop/Balada, Salsa...
Pop
AAA, Euro Pop, Power Pop, Pop Rock, J-Pop...
Talk & Poetry
Audio Blogs, Political, Sports, Religious...
World
Reggae, Traditional, World Fusion, New Age...
Alternative
Indie, Experimental, Grunge, Punk, Ska...
Blues
Straight Ahead Blues, Jump Blues, Blues Rock...
Comedy
Adult Humor, Political Humor, Prank Calls...
Electronica
Acid, Ambient, Drum n Bass, IDM, Mellow, Industrial...
Jazz
Smooth Jazz, Free Jazz, Fusion, Bebop, Swing...
Metal
Rap Metal, Goth, Heavy Metal, Death/Black Metal..
Rock
Classic, Unplugged, Surf, Rock En Espagnol, Punk...
Urban/R&B
Soul, Funk