title: Creating SEO friendly URLs in Rails 3
body: <p>I currently have URLs which look like this:</p>
  
  <pre><code>things?category_id=6&amp;country_id=17
  </code></pre>
  
  <p>and I would like to have URLs which look like this:</p>
  
  <pre><code>/printer_cartridges/united_kingdom
  </code></pre>
  
  <p>Is there a way in Rails 3, without hard coding all of the categories and countries in the router to have the URLs as I would like above, perhaps using <code>find_by_name</code> or the such like? What is the best way to approach this?</p>