The article Free Music List December 2005 was a very successful article back in 2005 and I finally found the time to update the article with new sites and get rid of links to sites that do not exist anymore. Most of the sites listed below allow downloads even for non registered users, several ask you to register after downloading some albums and some require a registration before you can start to download or stream music.
I added genres to several sites if it was obvious and did not mention one if the site offered more than one genre. Downloads means that you can directly download music - normally mp3 files - from the site while streaming means that you can stream the music on the website.
Take a look at my article about Grab++ for a possible method to download music from sites that stream music. Feel free to add any music site that you know and is not in the list.
Altsounds Alternative [streaming]
Fabchannel Concerts [streaming]
Musicovery Find new music [streaming]
Musicmesh Find similar artists [streaming]
Musipedia Midi Files [streaming]