You could plan ahead, as quiltstrinz implied, and have your next project ready to sort and cut.
Other things would include finishing binding a quilt, putting on a label, rewriting directions so you can follow them better [something I do a lot!], or any handwork.
I have yo-yo's ready to sew and some embroidery.
There is always something I can take. If worst came to worst, I could take quilt magazines and mark the ones I want to save on my computer for later use.