I am a witch, but I am also a poor witch :). As such I have to make use of things I use on a regular basis or which can be obtained very cheaply.
So I usually go through my cabinets and see what I have on hand and I always have some salt :). Salt is cheap, easy to use and can be used in a variety of ways.
Protection Magic- salt can be used in spells and rituals as a protection item. Add a few grains to a gris gris or mojo bag and you have a portable device for protection. You can also sprinkle salt around the area you are working in to protect from negative energies. For example to form a protective circle or a circle of salt around a mirror for scrying.
Kitchen Magic- when cooking meals, you can add herbs to infuse magic into your meals. Salt can be added for protection or purification/cleansing.
Ritual bathing- when I do rituals I always like to prepare by taking a ritual bath. The salt not only softens the skin but helps cleanse away physical dirt as well as negativity. The Egyptians used natron in all of their cleansing needs. You can even color bath salts for use in sympathetic magic as well. For example, using blue food coloring with salt and then adding to the bath can help facilitate healing magic.
Earth magic- salt is considered related to the element of earth (at least in my way of doing things). You can use salt as a consecration tool for cleansing altars and altar tools. Just be careful of what you use salt on, it can be abrasive to certain objects.
In most wiccan covens a ritual circle is usually cast prior to performing ritual. In some traditions, salt is mixed with water to help cast the circle.
I had a friend who used to live in an old plantation home. She complained of being able to feel this negative energy throughout the home, so we put together a cleansing party. Once we were able to complete the cleansing we also added salt around windows to keep out negative energies.
Do you use salt in your practice?