I've been seeing results from bent over, wide grip rows to the upper chest. Get about parallel and pull the bar up. It's builds the upper back nicely.
Another I've been experimenting with is to set the cables on a crossover machine down low, then grab the right cable with the left hand and the left cable with the right, take a step back, bend over, and perform the same movement as a bent over fly. I've only been doing them for about 2 weeks, but I get a nice pump back there that I don't get from any other exercise.