Nick Drake's "Family Tree", a collection of his home recordings, straight no-overdubs onto reel-to-reel with tape hiss in the background, sound fantastic. Much better than his overproduced studio albums, which are too easy-listening for me (the one exception being "Pink Moon", which uncoincidentally is also a straight voice-and-guitar no-overdubs album).
There's loads of singers I've found out about on myspace whose sound was so much better before the record deal. This is kind of a bad example, cos I don't rate her at all, and I never did, but I thought that the Florence & the Machine 'kiss with a fist' song had something. at least it sounded raw. whereas she's definitely been given the smoothed-out production treatment now.