1) Check the growth of mold in your humidifier by rinsing it out thoroughly, then adding 1/2 cup vinegar when refilling it with water.
2) Add about 1/4 cup of vinegar to the last rinse in just about any kind of laundry. The acid in vinegar is too mild to harm fabrics, yet strong enought to dissolve the alkalies in soaps and detergents. Beside removing soap, vinegar prevents yellowing, acts as a fabric softener and static cling reducer and attacks mold and mildew.
3) Add 1/2 cup of vinegar to prevent lint clinging to clothes.
4) Use vinegar in your final rinse for black washables. It removes soap residue that makes black clothes look dull.
5) Vinegar is good for the washing machine itself. Periodically run the machine with only a cup of vinegar in it--nothing else added to the wash cycle. Hoses will be cleaned and soap scum dissolved.