I love getting my wedding photos out to look through them, and wish I did the same for our guest messages. The wedding guest book of personal message is such a thing to be treasured and can be made as unique and creative as you like.
If you want to be able to see your messages more frequently then ask guests to sign a frame border that will then surround a wedding photograph on your wall. You can easily make your own by buying some mount board from an art shop and cut to the size of a large frame which you can get in charity shops or antique stores for a more ornate version. Alternatively try these from The Handcrafted Card Company
Why not get guests to write a thought or a wish on a little card and drop it into a vintage box which can become part of your home. You may have a box at home, or a shoe box decorated in decoupage, or you could buy a jewellery size box like the one from Touches Home Interiors.
One of the real weddings I have come across on the web had a beautiful idea from their twenties themed wedding. They cut squares of fabric for guests to write their messages on that would then be made into a wedding quilt. Get inspired here.