Psychic paper in books. My books would have more hot dudes doing romantic yet dangerous things than they do. Though I do believe that is the reason some people don't read - they just don't have the imagination.
You cannot pretend to read a book. Your eyes will give you away. So will your breathing. A person entranced by a book simply forgets to breathe. The house can catch alight and a reader deep in a book will not look up until the wallpaper is in flames.