Musopen This website is great for royality free music. It offers many songs from various artists. All audio files on Musopen are organized into composers, preformers, instruments and more.
WhoIsMatt
Offers many different songs and also other websites to find free music on.
CCMixer
This audio website has many different remixes available for use. Along with the remixes there are also many normal mixes of many songs.
OPSOUND
Along with various songs, this website offers new songs from the radio and many artists.