How can i keep our jack-o-lanterns from rotting?

It's still early, but soon the family and i will be out picking our pumpkins and carving scary faces into them as we do every year. This tradition, though, hardly seems worthwhile since our jack-o-lanterns never seem to make it past two weeks and by the time Holloween actually arrives, trick or treaters are frightened more by the mold and smell of rotting pumpkins than they are the scary faces. Is there any way to make our pumpkins last longer?