Sound and music

http://www.trackline.com/
Over 1000 tracks available as
file downloads or in convenient
themed collections on
Audio CD or CD-Rom.

http://freeplaymusic.com/
4217 tracks not full songs but sounds.
a marvelous temperament and engrossing, dramatic melodies to Acoustic Guitar Vol 6, featuring his excellently played and wonderfully recorded acoustic guitar.

http://www.nvmdigital.com/
Background music

http://derekaudette.ottawaarts.com/music.php
Lots of sample to find the right sound before purchase.

http://audiojungle.net/category/music?
A wide range of music but you have to pay alot to use the music.