Indoors, crown molding usually fits near or at the top of your wall against the ceiling. It can add to and dramatically change the whole appearance of any room. It can even have space behind the profile for lighting that will add to the appearence of everything in that room. Crown molding can even be used for tray ceilings.
Outdoors, a similar molding is a soffit molding and is made to fit under the soffit of your home. Soffit moldings are usually sized to the scale of the house. It goes without saying that you can have an elaborate or simple profile for your molding. Either way you will get a a look that will increase the overall apperance of your home or room!