When you go to a gym, the weight activity that most guys are doing is bicep curls. Mark Rippetoe says this is how you identify people who don't know what they are doing. What he is means is that before guys worry about working on specific muscles like the biceps, they need to develop the core body strength with exercises like squats, deadlifts and presses. The guys who spend their time just doing curls are beginners who will never be strong.
Yet it is the bicep flex that guys use to show how muscular and pumped they are. Show the guns!
There are machines and cables that help with curling (I occasionally use the Bisolator - love the name) . Dumbbells are more effective. A preacher bench is also a nice assist in bicep curls.