Several years ago, I was talking to a potential Dom, and I really liked the idea He had for disciplining His sub. It was all about reversing the impetus. If she talked back to Him, then she would be forbidden to speak for a time, possibly wearing a gag of some sort. If she started to see herself as His equal then she would be made to kneel next to Him and crawl if she needed to go somewhere. If she did something without asking His permission, she would have to ask permission before doing anything.
I thought this was a great way to discipline a sub. These punishments should, of course, be in addition to spanking and corner time. What are some other examples of reversing the impetus that you can think of?