Pat Parelli's 'Hide the Hiney' game.
Let's see if I can explain it (I'm REALLY bad at explaining things and them making sense
Ok, instead of staying in one place while your horse goes in a circle around you, go with your horse. With the hand that holds the rope attatched to her, stick it out and lead her (trotting).
Watch her tail, cause when you're stopping you're going to 'step on it' (not acctually step on it, but act like you're going to). Slide that hand that isn't holding the rope down the role and grab it. Pull the rope towards your bellybutton and 'step on her tail'. Your hors should stop, and face you directly so you can't see her hiney.
You can google 'Hide the Hiney' game if I didn't explain it clearly :)