Better biceps
Want biceps that turn heads? Well, for that to be the case you're going to need overall upper-arm development. And to develop the upper arm muscles requires getting them stronger; which requires the right exercises and loading.
Overall upper arm development
The upper arm ism just comprised of the biceps and, therefore, bicipital development is only part of an impressive arm. In fact the triceps contributes to most of the arm's circumference with additional mass coming from the brachialis (the bulbous muscle outside between tris and bis). As such attention to development of the tris and bis is critical to impressive arms (brachialis derives benefit from biceps work).
Strengthening the upper arm
In order to strengthen the upper arm, the amount of tension the bis and tris can generate must be increased. Increasing the tension capacity of the bis/tris is best done by demanding successively greater force output in exercises that allow high bis/tris tension. And contrary to pop-fitness assertions, multi-joint push/pull movements allow for greater progression than single-joint/low-force exercises.
Pushes and pulls for total arm development
Pullups/chin-ups
Pullup/chin-ups demand high amounts of tension from most of the upper arm; in fact, the long head of the triceps (flappy portion) crosses the shoulder joint and contributes greatly to overhead pulling. As such, pullups/chin-ups should be done by every arm enthusiast that can (gravitron/lat-pulldowns also good). Furthermore, it's critical to long term development of the upper arm to continually get stronger in these movements.
1 arm dumbbell rows
1-ADBR'S are also total arm builders. Rows allow for substantial progression and, therefore, build the involved muscles. Find anyone with heavy rowing strength and, very likely, she/he has well developed arms.
Close grip bench-presses
Close grip bench-presses can place tremendous tension on the lateral head of the triceps. Few exercises equal close grips for lateral head triceps development. Other than integrating close grips into your training regularly, all you have to do is get as strong as possible on them! See my article on bench-presses, as the disclosed techniques will also skyrocket close grips.
Dips
Like close grip bench-presses, dips place tremendous tension on the lateral head of the triceps. Additionally, the bis are required to create tension from a stretched position when dipping; which stimulates the bi's to grow also. The dip is also easily progressed easily via increased weight on a belt.
Conclusion
Impressive upper arms aren't just about the biceps, all the muscles must be developmed well. Great development requires a lot of tension that's progressively greater. Such great tension is best attained via multi-joint exercises. Overhead pulls and close grip bench-presses are two exercises that can forge impressive arms if substantial strength is gained on them!