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.
My personal project is finally finished. Exactly 98 Polaroids that I took over the past year with my love, family and friends and our favorite trips displayed in a customized picture frame in our living room.