my favorite are the one-arm cable rows, underhand grip pull-ups and pull downs, but you can't beat one-arm cable rows.
here's a tip, take a stool or something to sit on and go towards a cable machine. Position yourself so you can get a complete full stretch( i'm talking about your chest touching your knees) So, when you start your rep make sure your pinky is higher than your thumb and then twist the handle so the top of your hand is
parallel to the floor. A lot of people touch the ribs with the handle but I never could get a full stretch with this so I go a little further towards the outside and a little lower. Kudos to the Arnold Encyclodpedia...you should go buy it. BTW most people don't even work their back and especially kill for yours.