Ways to Shrink Drupal's Core?

This may be a more philosophical question than a direct call for technical help. But I'm looking for a CMS (I hope it to be Drupal) which can be scaled-down from an "everything but the kitchen sink" generalization to one specific to one task and one customer. I know there a many distributions which target different verticals, but still they are designed to meet every potential use and user within that narrow community. Aside from writing my own customized CMS (I've tried both Django and Rails) is there a way to retain Drupal core mission without all the clutter? For instance, use just one theme with one setup, one content type, one admin type, etc - jettisoning 90 percent of the code designed for a general audience?