Hammer curls on the sides of the body. VERY effective for the area in between the triceps and biceps ( the specific name on the muscle escapes me ). I use to hammer curl in the front of the body, however, when I started gettin' at higher weights I would feel, at times, my bicep tweak. And, obviously, not in a good way. To each his own though.

Btw, you can also use rope. Just clip the rope on a lower pulley and mimic the hammer curl. Works just as good, imo. Or, rather, in my personal experience.