An older cat showed me this exercise once, and i've never seen anyone else do it this way. That's not saying that other guys haven't done it this way, since I live in B.F.E. But this worked great for me.

Take a flat bench and lay it under a cable machine. Take a short straight bar, attatch it to the cable, and position it at just beyond arms reach as you are laying down on the flat bench with your feet facing away from the the cable machine.
Basically, you will lying down, pulling (curling) down the short straight bar until it reaches your nose (practically) and you hold it there for a moment, then slowly retract.

This is by far the best exercise I've ever used to get my biceps to "peak". This is one of the best exercises to keep a constant tension and resistance on your biceps. It's similar to using a cable machine with a preacher curl bench, but this is more effective because the angle causes more constant resistance.