How about autograph blocks, see crackerbox pattern:
http://www.quiltinaday.com/freepattern/
Get a solid cream like Kona Cotton for the autograph rectangle and use the rest of your fabrics for the blocks. Use enough blocks on each table runner for everyone to sign. Bring fabric pens for people to use.
Or just use patchwork with enough light blocks for people to sign on.
Do you have an embroidery machine? You could embroider everyone's name for place settings.