I take one for my belts, and I take one for flowers if I'm bringing them home. Poke a hole in the top and you can put it over a suit hanger in your garment bag. Or you can use it as an emergency tote or briefcase. Shampoo and conditioner. Shampoo can wash out lingerie and remove tough stains.
Conditioner really does make decent shaving cream, for face or legs.
Pack jewelry in them. Separate cosmetics with them. Use them for emergency washcloths. Just make sure they're free of chemicals before you do. Look behind the bathroom door.