I just heard a story on the radio about scientists 'freezing light'. OK, does not help you here but this was so cool. They shot a light pulse into a "frozen atom cloud" and even moved the cloud and heated it, and the light actually continued from its new location. They considered the light to be 'stopped' and said it was actually slowed to about 15mph. This will someday be of use, but for now it's just one of the most facinating things I have ever heard. Sorry if I waisted your time not giving you an answer, but your question reminded me of this report and it kinda blows my mind.
