These are useful. I keep one (with holes poked in its bottom) in the corner of my shower for holding up my razor, toothbrush, tongue scraper, etc., and I use a hanging utility cup for keeping soap dry.
Aluminum doesn't really rust like steel does, so it stays clean and attractive. Incidentally, you can use these to make the special bi-level planters, as shown on this website.
Utility cups can also be used in the fridge or freezer for individual dessert servings – particularly those that are layered – but do not use these cups for baking. [Aluminum cans are covered with an epoxy laquer preserve the freshness and taste of the beverage. This laquer is foodsafe and stable at room temperature or below, but at baking temperatures it risks contaminating your food.] You can scoop the dessert out of the can or peel the side off like an orange to reveal the layered sides of your dessert, if applicable.
These cups are not perfectly suitable for beer pong because their rim diameter is too small and their bottom diameter is too large, according to the official regulations. Still, you could make a simple skee ball setup using bouncing, rolled, or thrown ping pong balls.
Try making one of these into a vase, or a boquet of red-themed candies overflowing the top.
Adding a reinforcing band of plastic to the new rim of the can adds important rigidity.
Perhaps the simplest way to make a utility cup is to open it with a manual can opener. Then you can add a lid (search Amazon) to make a coin bank or a storage container for your fridge or lunch box. If you carefully stretch a rubber balloon over the top, the storage can becomes airtight.
By the way, if you make your own skee ball game out from lots of soda cans having the top cut off, then please send me a photo.
The Instructions page of this website explains how to remove the top and make a rim.