Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Webmasters Stack Exchange is a question and answer site for pro webmasters. It only takes a minute to sign up.
Is there a WYSIWYG editor that outputs markdown?
One excellent editor/writer on the Mac OS X platform is iA Writer. It's is beautiful and simple to use.
If you're looking for web-based options, look at CKEditor or TinyMCE.
See this answer also.