HDI display the human readable node type at the end of the breadcrumb I want to modify the default breadcrumb to append the machine readable string of the current node type to the breadcrumb. I believe I can do this via template.php.

I am using drupal 7.
I'm not used to doing stuff in the theme layer, so my solution would be to use a module. Have you seen this one: http://drupal.org/project/custom_breadcrumbs ? I think it would allow you to do what you want.