We use one to hang our hose on. We nailed it to the wall, snapped the cover on just to keep wasps out, and looped the hose over it. Could be used for electrical cords, binder twine or any other long string you want to hang neatly.
We also flipped one upside down, put a hole through the bottom, and hung it upside down over the top of our chicken feeder to keep rain out.
It's also great for clothespins.
I'm thinking it'd be simple to help kids turn this into a cute birdhouse. The lid would make it easy to clean out at the end of the year. Let them decorate, cut small hole of appropriate size in the side, add a perch (or not). Attach to tree (if you use a screw to attach it, you could easily get your screwdriver through the front hole for the bird to reach the screw.)
Use one in each vehicle and in the boat or on the tractor or in the barn to hold first aid supplies (I very rarely need a bandaid when I am in my bathroom...)
Use them to store small Christmas light strings or ornaments.
Keep one in each rain barrel as a water scoop.
When I worked in a daycare, I used a bunch of these as simple lightweight building blocks for the kids. They could pile them quickly to make a wall or a tower, and no one got hurt if they fell.
I've also used them to store small toys like Legos, hot wheel cars, doll clothes, magnets, marbles, plastic animals, toy people, blocks. I took pictures of the contents and taped it to the front with wide clear shipping tape. The picture made it easy for even little kids to help organize.
I've also used the same process to label and store things for Alzheimer's and dementia clients I worked with. Adding pictures makes it easy to identify and is much easier for dementia clients than words are.
Store puzzles. Cut out the picture and use clear shipping tape to tape it to the outside. They stack easily, and won't get damp.
I also used some in the basement, attic, and cellar to hold charcoal. Keep the lids off and the charcoal will absorb moisture. It keeps the cellar from getting musty. When the charcoal gets grey, they have absorbed the moisture. Dump in the compost pile, add more fresh charcoal, and repeat. (A piece of charcoal in a tool box will also help keep moisture and rust away from your tools.) Waaaaay cheaper than Damp Rid!
Store chalk so it stays dry.