rhonnie,
That "jumping up and shouting [b]STOP[/b] while clapping your hands" method sounds like it would be pretty effective but maybe not too practical in public :)
I have been using the "excuse me" method as mostly self talk. But I think I am going to start faking a sneeze when the thought begins, and then use the self talk "excuse me" bit.
In private, the sneeze can act as the shouting "stop" part, and in public most often a sneeze will bring a "bless you" from someone which will lead to a "thank you" from me and so re-direct my thoughts.
I will beat this thing yet and when I do, I will share with everyone.
Mike