Ice cube trays are incredibly useful to have around, because they can be used for more than just freezing water. In addition to freezing ice for drinks, ice cube trays can also be used to freeze things like stock for quick bouillon cubes and fruit puree for perfectly measured iced smoothies. You might also want to try freezing things like fresh fruit or herbs inside the ice, so that the ice cubes will be decorative and flavorful.
In addition to the familiar rectangles, ice cube trays can also be molded to yield an assortment of shapes. Squares, triangles, circles, and hearts are all fairly common, as are novelty shapes like LEGO® blocks, shamrocks, and animals. Sometimes, the shapes are designed for a specific purpose; long narrow ice cubes, for example, can be easily inserted into bottled beverages to keep them cool. These ice sticks can also be used in tall glasses for an unusual presentation of a cold beverage.