Recently I discovered how vinegar can be used in many alternative ways - as a cleaner, keeping hair looking shiny and healthy, helping relieve asthma, coughs and colds, helping eczema sufferers, as a deodorant - it has many many uses.
Hannibal Barca even relied on it when crossing the mountains to fight the Roman Empire.

Lemons are also useful for keeping in the fridge for stopping smells, cleaning limescale off taps even adding a small amount to dishwater to dissolve grease.

There must be many other ordinary household ingredients that can be used for all sorts of things, if you know any please share them here.