I grate my own Parmesan cheese (and others). When I get down to the rind, I usually throw it out. Is there a use for it?
Yes, you can save it and add it to soups such as Minestrone for additional flavor. Once the soup is done, remove and discard the rind. For extended storage, keep it in a bag in the freezer until you have need for it.
Save it! In addition to minestrone and other soups, it also works well to flavor sauces -my favorite use is in the mushroom mixture for chicken marsala.
Parmesan rind is really good in the Minestrone Soup. Also, try it the next time you are slow cooking your fresh tomato sauce. The rind adds just that certain something to the sauce that grating the cheese does not do.
I tipically eat it as is after have scrubbed\cleaned the paraffin with a knife.
For something original: put it in a microwave for 1 minute; it will inflate becoming crunchy.
No one's said risotto? Fine then, I'll say it.
In a restaurant my brother worked in they would cook the rind up in the pasta water for staff food. Then they would server the pasta with the chopped up rind in it. Apparently the pieces of rind were fought over.
If you have a blow-torch and a large enough piece of rind, you can heat the inside and use it as a serving dish for soups, pasta and other things.
Like everyone else is saying, toss it into anything that you a) simmer in water and b) want to taste good. For me, having a rind left over is always an excuse to make tomato sauce.
In Italy the rind is usually covered in transparent wax. Grate it even outside before using it!