From a New York Times interview with Columbia University professor of Buddhist studies (and Uma's dad), Mark Thurman:
What do you think about when you meditate?
Usually, some form of trying to excavate any kind of negative thing cycling in the mind and turn it toward the positive. For example, when I am annoyed with Dick Cheney, I meditate on how Dick Cheney was my mother in a previous life and nursed me at his breast.
Via Gene Healy.