The Black Keys' "Howlin' for You" is an homage to bluesman Howlin' Wolf. Here's a vid of one of his most famous songs (which, um, you have probably heard as background for certain pharmaceutical products). VH1's Metal Evolution shows this song as part of the evolution of music leading up to metal. At 6'5" and 275lbs, Howlin' Wolf got the reputation of shaking the foundations at gigs with his loud songs and big voice, but scaring the patrons half to death, especially when he sang some of his darker songs. He was metal, at least in his themes and presence, before there was metal.