For a holiday party: Fill balloons with water colored with food coloring. Set them out when it's below freezing. After they've frozen solid, remove the balloons and you'll have something resembling giant marbles.
For icy steps and sidewalks in freezing temperatures, mix 1 teaspoon of Dawn dishwashing liquid, 1 tablespoon of rubbing alcohol and gallon hot/warm water and pour over walkways. They won't refreeze. No more salt eating at the concrete in your sidewalks.