htmlXPress

It is a Perl script to parse web pages before publishing. User-defined place-holders of macros can be expanded.

Invisible comments and extra whitespace can be removed. Being Perl, it is essentially freely programmable to suite your website.
How do I use htmlXPress?
You copy the configuration file to the directory of your HTML source files and edit it. Here you define your own macros and general search and replace patterns. You also specify into which folder the result files should be saved to.
Site-specific settings can be defined through different config files in separate source folders.
Whenever an HTML file is ready for publishing you "compile" it with htmlXPress. In Mac OS X, you can do that directly from the command line in the Terminal:
% htmlXPress myfile.html