I love this idea. An envelope guest book. You just take a store-bought scrapbook/album and glue envelopes into it. Lay out colored pieces of paper for guests to jot notes down on, and then they can place them in the envelopes.
Whether you're hanging shiny red ornaments on fragrant green Christmas trees or mounting pretty green pine wreaths adorned with lovely red bows, red and green are the colors of Christmas. But don't feel limited to these classics when decking the halls.