Vinegar - Vinegar has lots of uses relating to cooking, canning, and food preservation. Its also useful in cleaning, unclogging and deodorizing drains and toilets, disinfecting cutting boards and counter-tops, eliminating mold & mildew, and polishing silver, brass & copper objects, Vinegar can be used to clean and sanitize canteens, water bottles, thermoses, jars, and other containers. Vinegar can be used to help remove the glue residue of bumper stickers, price tags, and decals. Pouring some vinegar on a rusty screw or hinge can help unstick it. Some folks even use vinegar soaked rags staked in and around their garden to keep out deer, dogs, rabbits, and raccoons, which can't stand the smell even after the vinegar has dried. A number of medical studies have shown many health benefits of vinegar, especially apple-cider vinegar, including improving insulin sensitivity and decreasing blood sugar levels (both fasting and post-meal) for folks with prediabetes and type 2 diabetes. My own experience as a type-2 diabetic has convinced me that consuming vinegar with a meal lowers my after-meal blood sugar spike by 25-40%. As with baking soda, the list of possible uses goes on and on and on. Just google "uses of vinegar" for lots more ideas.
Borax - Borax is best known for its use as a laundry detergent, but there are a myriad of other uses, too. Borax can be used for a large variety of cleaning tasks, including odor control, a very effective all-purpose cleaner, and removing mold, mildew, rust, and various types of stains. It can be used to unclog drains and toilets. Mixed with equal parts of sugar, it can be used as a bait to kill cockroaches, ants and other insect pests. Mixed with equal parts of salt, and a little elbow grease, it can be used to scrub clean cast iron cookware without leaving behind a soapy taste. Borax is a natural weed-killer. Borax can also be used in small amounts to fertilize boron-deficient soil (see the wikipedia article for instructions). Borax is also used in candle-making to treat wicks (makes them burn longer with less smoke and ash). Google "uses of boax" for many other ideas. Note: Borax can be toxic to people and pets. Store safely and do not consume borax.
Epsom Salt - Epsom Salt can be used to make a very relaxing soaking bath. It relieves pain, sprains, bruises, and muscle cramps. It is used to soothe tired aching feet, and fight foot and toe-nail fungus. It also makes for an excellent facial scrub and body wash. Mix with water and spray on the skin to reduce the itching from mosquito bites and insect stings. It also provides sunburn relief. Epsom salt can be used in the garden to control slugs, snails, and other pests. It also makes for a safe and natural insecticide spray. Adding a tablespoon of Epsom salt to the soil around each tomato plant is a great boost to tomato production. Other vegetables will also benefit from the magnesium in Epsom salt. Roses and houseplants may also benefit from small doses of Epsom salt. Google "uses of Epsom salt" for many, many other potential uses. Note: Even though Epsom salt is a type of magnesium-based “salt,” it should not be consumed like regular salt since it acts as a powerful laxative. If you do use it as a laxative, follow the directions on the package closely to prevent over-use.