CKEditor - Real-time collaborative future-ready rich text editor
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
txt2tags - It reads a text file with minimal markup such as **bold** and //italic// and converts it to the...
Trumbowyg - Feature-packed WYSIWYG editor in only 15kB of JavaScript
Texy! - Texy! is a lightweight markup language as well as converter of this format to XHTML, in a form of a...