Once we have a blog_id-based URL generator, we should add a

permalink_url

method to the content class, so we can do this:

   a = Article.find(42)
   a.permalink_url  
   => 'http://blog.example.com/articles/2006/08/11/didnt-do-anything-today'

We can then replace a ton of helpers and clean up a lot of code.