Leave a Polaroid camera next to your guestbook so your family and friends can tape pictures of themselves next to their messages. You can use a scrap book instead of an actual "guestbook" that gives them room to write advice to the new couple. You can also let them take a 2nd shot for them to keep. Just be sure to count the cost, and you may want to consider having someone "man" this area for you! Happy Planning!
