After Effects includes several built-in keying effects, as well as the Academy Award winning Keylight effect, which excels at professional-quality color keying. For information on the Keylight effect, see its documentation in this folder: Adobe After Effects CS3/Additional Documentation/Keylight.
To see a video tutorial on keying with Keylight, visit the Adobe website at www.adobe.com/go/vid0229.
Adobe Creative Suite Production Premium Edition also includes Adobe Ultra, which can quickly key out a poorly lit background shot with a low-quality webcam.