Remember, most of the time while your car is in motion, your intake will be ingesting air that's moving through the front of the car if you have an aftermarket setup. Adding just a hood scoop will do nor more for cooling the intake charge when the car is moving... it's basicly the same air. And when your car is idling, it's just slurping up the war underhood air anyways. Ideally, you'd want to move the point of intake into the fender, below the engine bay, or have the scoop (like Lou) port air directly into the filter box. Other than that, it's just cosmetic.
Although, that ain't a bad thing either. I think a couple of Trans-Am syle tunnels on the hood would be sweet. Just remember you have to deal with the center indentations in the hood.