Here is a list of available sites for downloadable music, sounds, and sound effects.
Partners in Rhyme | This website has music to download for Film, TV, Video, and Websites in addition to free sound effects, music loops, midi files, and audio software. All music is free and comes with a generous license agreement. They have a blog with tutorials and explanations of how to use the site here.
Free Music Archive | Free Music Archive is an interactive library with legal audio downloads directed by a freeform public radio station WFMU. Browse by curator or genre to download free music. Availability to set up an account, make a profile, become friends with other listeners, create and share mixes, and write posts on their personal blogs.
Royalty Free Music | This is a royalty free stock music library. It offers over 10,000 high-quality and royalty free stock music tracks in a variety of genres. The range of free items includes stock footage, and sound effects.
Jamendo | “World’s biggest free music library” with 418,000 tracks, 2 billion listens, and 154.8 downloads. It has free and unlimited listening and downloads. Uses reliable creative commons licenses for non-commercial use.
SoundBible | Offers free sound clips for download in either .wav or .mp3 formats. Includes sound clips, sound bites, and sound effects.
WolframTones | Create your own unique music for art, ringtones, and alerts. Generate your own personal composition by choosing a genre and then generating new sounds through pitch mapping and time controls.