I am all for repurposing fabrics etc, from jeans, skirts, and t-shirts to men's shirts.
If I find ugly or thin fabric that I wouldn't use for a quilt top or back, I WILL use it as a foundation (instead of paper) for string blocks.
I also have a few mattress pad covers that are in great condition but the material that is supposed to stretch down under the mattress tore and I am not into repairing it. I plan on using the mattress cover part as batt.