If you can't already tell, I like to find ways to personalize your wedding. Especially some of the smaller details. Most people read through their guest book once or twice and then it collects dust on the shelf. I came across a great idea on the Snippet and Ink blog.
The couple used Blurb to custom create a guest book using mementoes from their courtship (i.e. ticket stubs, photographs, etc.) They also had room for guests to sign. You could just do photos from your relationship, have room for people to write a message....the list goes on. Starting at about $20, it is an inexpensive way to create a keepsake that you will enjoy for years to come!