wedding guestbook. guest write their names & best wishes to the bride & groom on a stone with a permanent marker. then the newlyweds display the stones around their home. (in vases, in their front porch, bathrooms, living room, bedroom, office, kitchen, centerpieces, ect.)
Having empty chairs across from the bride and groom is a Scandinavian tradition. The signs aren't necessary, guest just know that they are invited to come and chat. This is a simple way to take the pressure off of the bride and groom to do a receiving line or make it around to every table to greet everyone. This way the newlyweds can actually sit and enjoy the meal and it's up to the guests to say hello.