How to keep your child from picking there nose?

How about every time he/she does it that you stop all activity and take them ceremoniously into the bathroom to wash their hands and brush their teeth.  That will get the point across that the habit is nasty and gross and won't be tolerated.  After a couple times of this washing and brushing, I bet they figure out more socially acceptable ways to clean their nose.

I could see how this would be effective for children of different ages as well.