You probably noticed back in the chapter on compound materials that a number of intriguing material types listed in the Material/Map Browser were not discussed. These material types are important, but they can't be classified as compound materials.
These specialized materials are sort of like your waffle iron. They're meant to be pulled out of your arsenal when you have a specific need. You wouldn't cook eggs on a waffle iron, would you?
The specialized materials include the Matte/Shadow material, the Ink 'n' Paint material, the Architectural materials, and the DirectX Shader material. These materials let you hide things in the scene, render the scene as a cartoon, use building materials, and view objects as they'll be seen in a game.
Even more special material types are listed after you enable the mental ray renderer. These materials are so specialized that they require a change in the rendering engine. These mental ray materials include an updated set of architectural materials, a Car Paint material, and several subsurface scattering materials.
With these specialized materials, you can create some really advanced, realistic results. Unfortunately they don't make waffles.
You can apply matte/shadow materials to objects to make portions ...