Most of us stretchers use plastic shopping bags to line small trash cans. What I do that I think is a little odd and fits this thread is I use any plastic bag that is large enough, as a liner. Bags from items like paper towels, the bag the tissue paper comes in, as long as there are no holes in it, a bag is a bag :)
Any cardboard packaging or the cardboard roll from inside paper towels, cereal boxes, any cardboard boxes get torn into small pieces and put inside a small kleenex box to use for fireplace kindling. This one I only do during fall and winter.
This one I've mentioned on here before, but I have a pencil holder I absolutely love and will never toss out. I made it out of a scrap of leftover wallpaper border that I pasted onto a washed can from frozen concentrate orange juice. It was a perfect fit lengthwise. Pretty blue roses (my favorite). I also have washed various sizes of tin cans and reuse them. I have a tiny tomato paste can that I keep paper clips in, and this is the odd one.. I regularly get new clean holders for the toilet brush. They are about 10. minimum to buy and I refuse to clean one of those! So occasionally I buy something in a large tin can like an oversized can of tomatoes or something know we will eat soon, and I wash out that tin can and voila, it's a fresh clean toilet brush holder. Sometimes I decorate them a bit if I'm feeling artsy but usually not. Once it is clean the tin can is pretty shiny.
The only other ones I can think of offhand are the pretty usual ones.. will try to think of more. Great thread!