CSS Mockups for Ads

Occasionally I need to mockup where the ads are going to go in an application (it has to pay for itself somehow, right?). Rather than putting the ads into the application while I am still doing development, I use some simple CSS to put a placeholder where the ads will go. In Rails, it looks like this:

  <% if RAILS_ENV == 'production' -%>  
    
  <% else -%>  
    Ads Go Here
  <% end -%>  

Then I can use my simple ad template CSS to make it standout. Check out the css source on Github