Stackoverflow's reverse-engineered WYSIWYM editor

If you want a lightweight, yet advanced (especially if you want it for a website for developers) online wysiwym editor, I suggest you take a look at Stackoverflow's reverse-engineered WMD Editor.

To download it, visit their development folder at github: http://github.com/derobins/wmd

Click here for a demo

Note that in the demo, I used the wmd along with a modified Stackoverflow css file.