markItUp! is a JavaScript plugin built on the jQuery library. It allows you to turn any textarea into a markup editor. Html, Textile, Wiki Syntax, Markdown, BBcode or even your own Markup system can be easily implemented. markItUp! is not meant to be a “Full-Features-Out-of-the-Box”-editor. Instead it is a very lightweight, customizable and flexible engine made to meet the developer’s needs in their CMSes, blogs, forums or websites.

markItUp! is released under both the MIT and GPL Open Source licenses. In short, this means that markItUp! is totally Free, and you can do whatever you want with it. You are only obligated to keep the credits in place. Check out the examples yourself.

Requirements: jQuery 1.2 Javascript library
Demo: http://markitup.jaysalvat.com/examples/
License: MIT / GPL License