Guest book idea: Have someone in charge of taking Polaroid pictures of the guests as they walk in. After the picture is taken, have them insert them into self adhesive photo corners in the sign in book and write a note next to it.
You could have a Polaroid camera with the guestbook. The guests would snap a pic and then stick it to the page and write their note to you! I love this idea, gotta find a Polaroid camera now! LOVE THIS IDEA!