I also do most of what's already been posted. I also use common items like bleach bottles for water storage or for repairs. For example, I often pick up coolers with broken hinges free at the recycling transfer station or garage sales. These are an easy fix with a piece of bleach bottle plastic. Simply unscrew the hinges, cut a piece of plastic to match the dimensions of the hinges, then place between the hinges and cooler and screw into place. This works really well and lasts for a very long time.
I also pick up coolers without lids at recycling or along the highway - these are used to water livestock. The insulated sides keep the water a little cooler in the summer and keep it from freezing as fast in the winter. I also stick them below the barn eaves to catch rainwater.
I save the napkins I get with occasional take out meals (along with all the other goodies that come along with them), and use these on top of newspaper to drain bacon grease. I also use them like paper towels, which I buy, but try to use very sparingly. I use napkins or paper towels rather than TP for nose blowing - sturdier. which comes in handy when you are working outside in the cold.
I also use the arms of old T-shirts for hankerchiefs. The bodies of old, worn out T-shirts and nightshirts I rip into long continuous strips that I hope to crochet into rag rugs this winter. Any left over pieces that aren't turned into hankies, are used as rags and can be tossed in the fire after they are no longer worth washing and reusing.
I cut nearly worn out towels into squares, zigzag around the edges a couple times and use these as TC (toilet cloth) to replace TP. While I only use them for #1, it saves me while a lot of $$ on TP, and they are softer on the bum, with no pilling. They are placed in a separate wastebasket next to the toilet until wash day, and I have never noticed an odor from them (I have a keen nose for odors). Then I run them through a small load short wash with a bit of bleach before washing them with the rest of the whites. Very little effort involved and I'm not wasting my money on something that is flushed or burned.
If I were not able to get more TP, I'd use TC and soak the ones used for #2 before washing with some bleach and homemade soap. It really doesn't take much to get them clean again. If I was not able to use the washer, I could (and have done, so I know it works) simply place them in a couple gallons of hot water (heated on woodstove, if necessary), add soap and bleach, and agitate with a toilet plunger until clean. Intermittent plunging and soaking works well, and you can do it while also doing other household tasks.
I save the feedsacks that are made of tarp material - they are used for everything from covering small items to keep dry, to gathering fire starting materials and scrap wood. They can be used to make sandbags, and I have in mind an eventual project of making a root cellar/storm shelter out of them. I have a friend who makes shopping totes out of the tarp material dog food bags.
Paper feed sacks are nearly impossible to find anymore, but I used them in the garden for mulch and weed suppression for years. I still save cardboard, from cereal boxes to large sheets of cardboard in the garden.
I know it's not pc, but I do burn any plastics that cannot be recycled into something else. Mixed in with other fire starting materials in my woodstove, they are excellent for getting a stubborn fire to go, and can't be any worse than using wax or pouring oil on the wood. Speaking of wax, I recycle wax into new candles and use the nasty bits left over to pour over saved dryer lint or sawdust in egg cartons to make firestarters.
Cans can be recycled into vases for decorating graves on Memorial Day, made into cookie and biscuit cutters, feed scoops, and pots for seedlings, or used to hold waste fat from cooking.
I reuse canning lids if they aren't visibly bent and still have a "new" finish on the underside. I seldom have a failure. Any lids not fit for canning are used for dry good storage or covering mason jars of coffee or leftovers in the fridge.
Rather than buying SOS pads, I use 000 steel wool from the hardware section - pulling off a small piece as needed for the job at hand. I use my own soap or dish washing detergent instead of the SOS pad soap. Saves quite a bit of the cost, as a package of the steel wool is only a couple bucks and lasts for years, while 12 SOS pads will cost more than that, and not last nearly so long. Oh, and if the piece of steel wool I'm using isn't worn out, I store it in the freezer - keeps it from rusting so I can use it again.
I save every bucket I can find and use them until they are literally breaking apart. Even then, they can be cut horizontally into rings to put around shrubs and trees to hold the water close to the plant rather than letting it run off and be wasted, and the bottom section can be used as a feed pan. I've done this with buckets that are so stuck together that I just can't get them apart, too.
Check out the Tightwad Tip thread and archives in Countryside Families forum near the top of the HT page for lots more ways to save and reuse.
I think it's easier to list the things I DON'T try to find another use for, lol. It hurts my frugal bone to throw something out without assessing it for further use.