I was reading an interesting article in the newspaper yesterday about how large office buildings in New York City are using large amounts of Ice in favor of traditional air conditioners. And... they are saving lots of money by doing so.
While it does take energy to make the ice, much more energy is saved using this method vs standard air conditioning. The article states that one building, Credit Suisse, is saving 2.15 million kilowatt-hours annually, which at current power prices would be over $300,000 in savings annually. The actual savings may be much higher than my calculation since the ice is made during off-peak hours, and the energy is saved during peak hours.