Mount your engagement photo with a wide matte around the photo, and have guests sign the matte. Later, you can frame the photo to hang in your new home.
Others are asking guests to sign labels or beautiful scraps of paper to incorporate into their wedding scrapbook.
We've seen guests sign guitars for their musically-inclined newlywed.
Draw a beautiful tree with lots of branches and ask guests to put their thumbprint on the tree and sign their names.
While some couples choose to have no guest book, consider that your wedding day is very busy and later you may not remember everyone who was there. A guest book -- in whatever format -- is a great way to look back at who attended your special day.