Awesome

Wiky: A Bidirectional Markup Converter

Wiky is a CommonJS port of same named clientside Wiki markup to HTML converter library written in javascript. As it is bidirectional, it can convert Wiki markup to [HTML] and later convert that generated [HTML] text back to Wiki markup. Optionally Wiky will create math formulas from a simple notation similar to LaTeX.

Wiky is neither an editor nor a widget, though it might be used by these. It is just a converter.

You can play with it in the WikyBox
You can find original project here

Package is available freely under the Creative Commons GNU LGPL License.