Well, just earlier I used two to extend a dog lead and tether it at the pub.

In sight of me, a couple are looped through jacket tags holding them onto a skinny rack clothes hangers don’t fit on. My house keys hang off a small one so I can clip them on and off my car key and 4×4 key. I clip on lock keys as well if I’m going mountain biking. Another has a dog training clicker and treat bag on the outside of my backpack. There’s a few holding up shoes and accessory ropes on my outdoor/climbing gear rack.

Other common things, though… Holding up things like lighting, bins, cooking stuff when I camp. Clipping through tied up bin bags so I can take them all outside easier and cleaner—basically anything with a small loop, they become a clip in handle. They’re great for undoing tight knots instead of finger nails. Switching weights in and out of my harness for different exercises on the pull-up bar or hangboard.

Most situations needing a handle, hook, ring, or knot, but faster and easier. I have a lot of very strong climbing ones, but decent ones that’ll statically handle up to 100kg—but try not to ever go half the Max static rating for safety—are light, tough, and very cheap.

That should give you plenty of ideas to work with :)

If you have a courier bag, you can use the karabiner to hang another bag to carry unplanned extra stuff when cycling. Keeps it out of the way in a stable position that doesn’t swing around.

Combine that with some electrical tape and you can even carry boxes or awkward shaped items.