I've registered for and now used Free All Music a couple of times. In return for watching ads, you get five free MP3 downloads per week. It doesn't work very well for classical. But in the jazz catalog, I did stumble on Ella Fitzgerald singing Sunshine of Your Love, the hit by Cream.
Do the advertisers get value from this site? Not clear; the only ads I remember thirty minutes later are a public service announcement about not denigrating gays and an ad for some kind of gadget charger pad.
Most of the lyrics to "Sunshine of Your Love" were written during an all-night creative session between Bruce and Brown, a poet who worked with the band: "I picked up my double bass and played the riff. Pete looked out the window and the sun was coming up. He wrote 'It's getting near dawn and lights close their tired eyes…'" Clapton later wrote the chorus ("I've been waiting so long…") which also yielded the song's title.