We've all done the dumbbell curl, but if you're actually trying to isolate your biceps a little better (when I say "better", I mean "without cheating as much"), then I totally recommend trying out the incline dumbbell curl. Here's how it is done:
Find the incline bench at your fitness center; it will usually be its own matter, but occasionally you'll need to actually pull the pin out and lift the normal seat yourself. Sit down on it with a dumbbell in each hand. (If this is your very first time going it, then I recommend starting with about five pound less in each hand then you would ordinarily do with the routine Dumbbell Curl) Beginning with your arms hanging loosely down by your sides.
As always, remember to keep your elbows close to your sides and just in front of your body (torso). Slowly begin to lift both arms - at the exact same time - in the regular motion of curling, and cease when you can't lift them up any higher. Be sure to keep your arms balanced and as steady as you can while doing this face lift.
Pause when you get to the top of the elevator, then slowly lower your arms back down to where you started.
At the base, count to three to three and a half before beginning another repeat. This should keep you from depending on the momentum of your arms to swing the dumbbells back up.
If done correctly, this really should minimize cheating, thereby giving yourself a much better work out.