Over the last couple of years, our development approach has shifted considerably. When we originally began doing client work, we regularly used a fairly wide variety of tools (Wordpress, custom apps in PHP, Ruby on Rails, or Java enterprise) in addition to Drupal to accomplish our clients' wide variety of projects.
Since the release of Drupal 5 & 6, we've seen the Drupal project mature into a very capable general purpose tool. As a result, we've transitioned away from having a large toolbox of languages and tools to use on a given project, to building most of our projects on Drupal.