4 web designs built on the same Drupal theme

Many of our early Drupal sites (Drupal 4 and 5) were derived from Blue Marine, one of the default themes that still "ships" with Drupal. All four of the above sites -- Boeger Web, MCC Water, Jake Schepps, and gfire -- all started with Blue Marine but then got advanced navigation treatments and other customizations to make them almost unrecognizable from the original.