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I saw this on some website, how to sharpen your knives using a ceramic coffee mug. I scoffed at it...went and found a large knife we had, did exactly what the guy did, and there was absolutely no difference.
Here's a vid that similar, could be the same one, it was so long ago:
http://www.youtube.com/watch?v=qM3aFmFj0fE
Maybe it will work for someone else, but made no difference when I tried it.