Naxos Music Library * allows you to listen to almost 115,000 streaming albums. Many different record labels, including the prestigious Sony Classical, reside here. While mainly focused on Western art music, a decent selection of world music can be found here as well.
Classical Music Library * is similar to Naxos Music Library but a bit smaller (it still has over 60,000 albums, so not too shabby). It is generally easier to browse than Naxos.
Jazz Music Library * has almost 1,000,000 tracks (that's over 65,000 albums if you're counting) of jazz, swing, bop, dixieland, etc.
Smithsonian Global Sound * is known for providing recordings from the Smithsonian Folkways Recordings labels. Music found in this database represents traditional cultures across the world from Armenia to Zimbabwe.
American Song * allows people to listen to music from America's past. Includes songs by and about American Indians, immigrants, slaves, pioneers, and cowboys. Includes songs from the Civil Rights movements, political campaigns, the Civil War, and the Revolutionary War.
Medici.tv * has over 1000 videos of concerts, recitals, masterclasses, and music documentaries. It also provides regular access to high quality live streaming performances from all over the globe.
Opera in Video * has almost 300 full operas. Most of the videos available are of staged opera productions, but there are also some documentaries and interviews with singers and conductors.