I live alone, and usually when I cook, I wind up with leftovers that I later microwave.
I usually cover a bowl or dish with plastic wrap prior to heating to keep the food from drying out,to decrease the time, and to keep food from spattering all over the inside of the oven. I hate peeling the wrap off and getting that burning steam released; it's a particular pain when I want to remove the wrap, mix the contents of a bowl, then heat it some more.
Recently, I had the wrap out to nuke some soup. I had just washed some dishes, and had a storage bowl and lid sitting on the sideboard. Hmmm. I put the lid of the Rubbermaid Stainshield over my soup bowl, (it didn't seal, just covered it) and put it in the microwave. It kept the heat in, stopped the spattering, and all I had to do was lift it, stir the soup, recover and return to the oven. It worked perfectly.
It's easy to wash afterward, too.
It can then return to being the lid of a storage container, but I suspect it will get a lot more use in the microwave.
Here's a review from epinions, where I got the illustration.