We took a neat twist on the traditional guestbook. In ours, guests are invited to write their wish for us on a small card and slip it into an empty envelope. It's a neat way to store sentiments and it gives a special feeling to each note as opposed to just signing your name on lined paper.
I used fabric and paper left over from making our invitations, so everything ties in together. The little envelopes were purchased at Hobby Lobby.
The greatest thing about this guest book is that it's made from a regular scrapbook. I plan to make it into a "guest book/scrapbook/photo album" of sorts for our wedding. Ideally, it will include as many photos as possible, our invitation, programs, etc. A nice way to have everything in one spot.