Spider Curls/Hanging Curls
I've done lots of variations on Curls and a few variations on a hanging/spider curl. The benefits of using Curls where your body is stabilized and your arm is hanging is the inability to CHEAT!
Whenever you're curling past the 8 rep range things are going to start to burn. The pump gets uncomfortable, and your body is going to convince you to swing the weight into a better position so you aren't in as much "pain."
That's why you eliminate temptation! This is an excellent bicep exercise. You can lean yourself against an upright bench, a nearby machine, or use a T-Bar Row station (like I'm doing in this video.)
With this you can really get a full range of motion and get one helluva contraction!