Most of my ideas are already posted here, but I'll just add my 2 cents worth - I sew them together, use them for smaller projects, stuff them into cat toys, donate tiny snippets for animal beds.
I don't think a single piece of batting or fabric sees the trash can at my house. I can't afford to do that. Even if I had the money to burn, my conscience would be burning if I threw scraps away. Too many people/charities could use what I no longer find useful. It may take a bit of time and organization, but I believe every effort on every person's part to prevent landfill use matters.
when I started saving tiny snippets of fabric and batting to donate to a pet bed making charity, I was blown away by how quickly I filled up a container. (I'm talking SMALL pieces - less than 2 1/2 inches square.) My favorite QS takes them and passes them on. It is very easy to take a bag of scraps and set them in their back room when I shop. I feel like I am contributing something useful. As they say, "One person's trash is another person's treasure!"