• 3Hive
• AccuRadio
• AOL Radio Guide
• BBC Music
• BBC Radio2: Sold on Song
• CBC Radio2
• Classical Live Radio
• TheClassicalStation
• Grooveshark
• icecast.org
• iLike
• Jango
• LastFM
• ListenLive.eu
• Live365
• Musicnow.fm (video)
• Musicovery
• National Jukebox
• NPR Music
• Our Stage
• Pandora
• PureVolume
• Shoutcast
• Slacker
• Songza
• Soundclick
• thesixtyone
• VaultRadio
• We7
• Yahoo! Music

• 10 Sites for Free Christmas Music
• American Public Media
• Archive.org: Audio
• BeeMP3 (search)
• Boston Symphony Orchestra: Media Center
• CCMixter (remix, share)
• ClassicCat (index)
• Complete Guide to Free Music Online
• Creative Commons Audio
• DeweyMusic (archive.org)
• Digital History Music
• Free MP3 Downloads (links)
• Free Music Archive
• FreeSound.org (clips, sound effects)
• ibeat Music Samples
• Incompetech
• Jamendo
• Mercury Theatre (old radio classics)
• MobyGratis (from musician moby)
• MP3.com (registration required)
• Musopen
• MySoundFX
• The Naked Violin
• National Geographic: World Music
• Open Music Archive
• OpSound (remix, share)
• Public Domain Information Project
• Purple Planet
• QTrax (has own player)
• Royalty Free Music Clips
• SoundBible (sound clips)
• Sound Sundays: 10 Albums Each Week
• The Wired CD

Podsafe Music

Podsafe music is specifically free for use in podcasting. Attribution may be required.

• Podmusic Countdown
• Podsafe Music Daily
• Podsafe Music Radio Network
• Podseek: Podsafe Resources
• Rewind Podshow

Royalty Free Music

• Chris Worth Productions
• FotoSearch: Stock Music
• incompetech
• Magnatune
• JewelBeat
• SoundJay
• soundzabound

Remember!
Just because something is free to listen to or free to download doesn't make it free of copyright! Be sure to check the LICENSE information for each site or artist to see the permissions for their music!