Broth is a lovely base for soups and sauces and makes a great addition to many casseroles. Best of all, you can make it at home for just pennies.
When you eat chicken, throw the leftover bones into your "chicken bone bag" in the freezer. Keep beef bones in a separate bag. When you have a supply of one or the other, make a pot of broth.
Small amount of vinegar
Vinegar is optional, but will help leach minerals out of the bones and into your broth.
Seasonings such as celery leaves, onions, and garlic (optional)
Vegetables may be left whole--they'll be easier to remove later.
Salt to taste (optional)
I prefer to leave broth unsalted, then season when I'm using it in a recipe.
Place bones in stockpot. Cover with water and add seasonings and vinegar. Place on stovetop on very low heat. (I've never used a crockpot for this, but it should work.) Simmer for at least eight hours--24 hours is better. (The longer you simmer the broth, the better the flavor... up to a point!) Allow to cool. Remove bones and vegetables. Broth may be used immediately, or I prefer to have it frozen in recipe-sized amounts for later use.