Free HTML Editors

Maqetta is an open source project that provides WYSIWYG visual authoring of HTML5 user interfaces. The Maqetta application itself is authored in HTML, and therefore runs in the browser without requiring additional plugins or downloads. You can run it remotely or download it and run it locally. Allows creation of interfaces for mobile devices. (You need to register with a valid email.)

KompoZer is a complete web authoring system that combines web file management and easy-to-use WYSIWYG web page editing.

Microsoft Expression Web 4 (Free Version)
Expression Web is a full-featured professional tool for designing, developing, and publishing compelling, feature-rich websites that conform to web standards.

Website Builder 4
A dizzying array of features that I haven't had time to try out yet, but include dCodes Integration,Over 1500+ HTML Shortcodes. Add Facebook, Twitter, Social Media connections, buttons, pricing tables, sliders and more.

BlueGriffon is a new WYSIWYG content editor for the World Wide Web. Powered by Gecko, the rendering engine of Firefox, it's a modern and robust solution to edit Web pages in conformance to the latest Web Standards.

Aptana Studio 3
Based on Eclipse, it supports JavaScript, HTML, DOM and CSS with code-completion, outlining, JavaScript debugging, error and warning notifications and integrated documentation. Additional plugins allow support for Ruby on Rails, PHP, Python, Perl,[1] Adobe AIR, Apple iPhone and Nokia WRT (Web Runtime).

This is a link to the previous version of my favorite free HTML editor. Unfortunately, it looks like this may be the last free version.

Amaya is a complete web browsing and authoring environment and comes equipped with a "WYSIWYG style" of interface, similar to that of the most popular commercial browsers.

Araneae is a text editor for html files with syntax highlighting, unlimited document length, drag-and-drop image support, instant browser preview, multiple documents open at once via a tabbed interface, and support for multiple languages. Freeware for Windows 95/98/ME/NT/2000/XP.

I have not tried it yet, but according to the website it includes syntax highlighting for php and css in addition to html. It appears to be no longer supported.

Simple customizable HTML editor with syntax highlighting, built-in-browser and various other features.