Why have a plain old book for your guests to sign! I love how these couples used things that fit the couple or their theme.
A surfboard for a beach wedding (or if you are big surfers) – how cool would that look on a wall in your house to remember your day! I love the signed wine bottle. Perfect for a vineyard wedding and you can keep it to open on your 10th, 20th, etc anniversary. The flip-flop book idea is another creative idea for a beach wedding. Love the signed guitar for the music fan.
What are you planning to use or did use for your guest book?