I just did my back day yesterday, and granted, it hardly ever gets sore, but I do get it sometimes. Here's what I go for.
3 sets of 10 pull ups, with a pretty wide grip.
3 sets of seated one handed cable rows;.
http://www.exrx.net/WeightExercises/BackGeneral/CBOneArmRow.html
3 sets of bent over rows.
http://www.exrx.net/WeightExercises/BackGeneral/LVInclineRow.html
and 3 sets of vertical lat press downs, they're weird, but pretty tough if you do them right. It's kind of like the following link, except my buddy and I do them standing up, with the lat pull down bar. You stand, face the bar, grip it pretty close, and push it down until your arms hit your sides, but keep your shoulders back...
http://www.exrx.net/WeightExercises/LatissimusDorsi/CBShoulderExtension.html
We've been experimenting with a week of 10 x 10 x 10 and then a week of 10 x 8 x 6. The 10 x 10 x 10 will give you that soreness you want, but it doesn't seem to make the gains go up as fast. However, when you do gain with a 10x8x6 workout, you'll be able to maintain it easily b ecause of the added endurance of the 10x10x10. At least that's our hypothesis so far...