Why do you keep erasers in your quilt supplies?

Is a question I got while we where unpacking our new place and a number of erasers fell out. Well apart from being handy when removing marks from fabric it has another great use:

When working with and cutting fuzzy fabrics like flannels and brushed cottons, my cutting mat quickly gets deep ridges in it with little threads of fabric. These are very annoying and quickly makes it hard to cut and they're very annoying to get rid of by hand. Then one of my handy erasers gets brought out and a quick rub over my cutting mat it does wonders, and even if it's if not as good as new, it's very much usable again =)