Saw this today and thought, why didn't I think of that! I will be making a few of these for our coolers. Typically just freeze jugs of water for the coolers when we camp. These would be a bit more compact in the cooler and the freezer. only draw back is you can't drink the water if you need to.
http://www.sheltonproducts.com/Coolertips.html
http://www.sheltonproducts.com/Coolertips.html