There’s a new article on MacDevCenter which explains various HTML Tools on the Mac OS X commandline (read: Terminal.app).
CLI Tools (especially on unix-based systems) have a high amount of features which can be utilized to solve certain specific tasks via shell- or apple-scripts. Even Automator allows to include cli tools into it’s workflows.
This MacDevCenter Article explains how to use some tools so you can modify or create html-files on the fly.