Recently I have been listening to a lot of John Cale. He is a very under appreciated icon in the rock 'n roll world. The Velvet Undergound and Nico is regarded as one of the greatest albums of all time. The Stooges debut album (produced by John Cale) is another iconic album. Not to be forgotten is John's work with Terry Riley, Nick Drake, and one of my favorite people of all time, Brian Eno. Also, John's boxset "New York In The 1960's" was quite revolutionary for it's time.
Over the years John has released many solo albums, most famously "Paris 1919" in 1973. In the past 3 years he has released 2 albums that have recieved critical acclaim but have fallen on deaf ears. Here are a few cuts from those marvelous outings that I recommend picking up (I'm sure you can get them for cheap used). His solo released have always been progressive.
from 2003's Hobosapiens
Look Horizon (feat. Brian Eno's daughters)
from 2005's blackAcetate
The Velvet Underground - Run Run Run