Free text editors may have a WYSIWYG component, but they are primarily used for writing HTML from scratch. Most text editors require that you know or be willing to learn HTML, but they are often faster to use for experienced developers. These Web editors all allow you to edit the HTML source and are completely free.
Creatext is intended to be an XHTML editor that goes along with your WYSIWYG editor. First you build your pages in the WYSIWYG editor, and then you use Crea:text to modify it so that it looks good in every browser. Feature highlights: Advanced CSS support, built-in validator, and international support as well as color coded XHTML editing.
jEdit is a text editor written in Java. It is primarily a text editor, but includes things like support for unicode, color coding, and allows for macros to add-in features. Feature highlights: XML support, scripting support, advanced CSS support, and international support as well as color coded text XHTML editing.
Xeena is a free XML editor from IBM. It can be used to edit Web pages as well as XML. You need to get an IBM account to download.
Vim is an extended version of vi. It has all the benefits of vi plus some improvements. It's not as readily available on Linux systems as vi is, but when it's available it can really help streamline your Web editing. Vim is not specifically a Web editor, but as a text editor it's one of my favorites.
One of the best things about vi is that it is ubiquitous. If you build a Web page on Unix or Macintosh servers vi will be available for you to edit with. It can be hard to learn and doesn't offer a lot of extra features, but the fact that it's everywhere makes it very useful to know. Feature highlights: text editor, some versions have color coding.
More than just an HTML editor Emilé is actually an XML editor for the Macintosh. It isn't optimized for the PowerPC, but it does work well, and functions as an XHTML editor as well.
Alpha is primarily a text editor that allows Tcl scripting to enhance it's functionality. It does support XML as well as HTML editing. Feature highlights: XML support.
TextEdit is the free text editor that comes with Macintosh OS X systems. It doesn't have a lot of features specifically for Web development, but if you want to start quickly writing HTML and don't want to have to download anything, this is a great place to start.
