Not just for ice anymore!
I use them to freeze milk too - the kind towards the end of the jug - you know what I mean, it's not spoiled, but nobody wants to drink that 'old' milk when there is a fresh new jug right beside it. So I take the milk no one wants (when it's iffy but not actually bad) and freeze it in ice cube trays then pop them out into a big zippie bag. So, when I'm baking or cooking and a recipe calls for milk, I can use up the 'old' milk instead of my fresh milk. No waste!
I also use ice cube trays for leftover bits of pizza sauce, spaghetti sauce, chicken broth, etc. Just have your collections in different bags. Thaw in the microwave for a minute or so and you're ready to go. If you like to drink tea, but don't like the way ice dilutes it, make a tray of ice tea cubes and use those in your tea
One of my friends told me she does this with cream of mushroom soup too - she said it separates just a little bit when thawed, but that a quick whisk fixes that and she's ready to go again. She likes to buy the huge can and separate it out to save money since cream of whatever soup is so expensive. If you try this, let me know what you think. If I try it I will definitely post a review.