tag me rich
with a WYSIWYG
Three rich-text editors I found that are cross browser/cross platform and create relatively clean HTML code.
- FCKeditor

Internet Explorer 5.5+ and Gecko browser (Mozilla / Firefox / Netscape) compatibility - TinyMCE
(JavaScript based)
Mozilla, MSIE and FireFox (Safari experimental) - RTE

IE5+/Mozilla 1.3+/Mozilla Firebird/Firefox 0.6.1+/Netscape 7.1+
I found the above three in a table of most, if not all, WYSIWYG rich text web editors for comparison.