Open Source WYSIWYG Editor

Nvu is the new Web editing environment based on the Mozilla platform and its Gecko layout engine. Primarily made for Linspire and other Linux flavors, its cross-platform architecture makes it available on a wide variety of other platforms.

Nvu binary test builds are now available for Linux, Windows, Mac OS X and FreeBSD.

NVU

Another open source editor that you can try out is openWYSIWYG.