The pioneering hip-hop group De La Soulrecently offered their entire discography for free - the interesting bit is that it seems that the move wasn't cleared with their label, Warner Music Group. ReCode has an interesting look at how the albums aren't available for digital purchase anywhere and were made available through a Russian piracy site.
I realized that the MP3s were CD rips taken from that Russian website when there was a link to that site the the song's "comments" section on iTunes. ha but awesome though. There most recent albums though weren't even part of this.
It's interesting that the songs aren't legally available in digital format. Warner must not think it's profitable enough to navigate around the sampling royalty stuff. If they really wanted to release it digitally, they would.