Anything to do with wedding and vintage immediately catches my eye.  I saw someone choose an old style key like this one above, add a classic tag with your guests names and voila!  A really nice vintage feel and something that looks a little different.  Your guests can keep the key as a momento of your wedding day for years to come.  You can pick these keys up in your local  brick-a-brack shop for ten a penny.  Why not give it a go!