I love this very unique idea from Cut the Cake Designs. Instead of a guestbook, let your guests send you lovely wishes on postcards. It's the Postcard Guest Book. Have your guest fill out these cards at your wedding. By the time you get home from your honeymoon, you and your hubby (or wife) can read all of the lovely wishes.
The set includes 100 post cards printed on 110 lb white cardstock. Cards can be changed to match your wedding colors. You can get your set on their web site.