title: Listing the most popular 8 city (custom fields) as used in posts
body: <p>Hi there i am creating a theme for a classifieds website and want to list the top 8 popular city which mentioned as posts custom fields. That means the top 8 cities which have the most classifieds. it will looks like this</p>
  
  <p><a href="http://i50.tinypic.com/6f7fww.png" rel="nofollow">http://i50.tinypic.com/6f7fww.png</a></p>
  
  <p>i saw some examples of sorting custom fields but couldn't manage to make it work properly.</p>