Musicians are always on the cutting edge; they saw the income gap before the rest of us — and wrote and sang about it.
Paul Rothberg at The Nation compiled 10 songs on this topic. Here’s one: “Brother Can You Spare a Dime” by the very raspy-voiced Tom Waites.
You might also want to check out the Social Justice Song Index.
Ann Powers analyzes this trend for Slate. She gives the bump to Kanye West’s “Blood on the Leaves.”