Markdown is a very simple programming language that is used to construct documentation. Have you ever done battle with the default wordpress plugin and ultimately resorted to using the HTML editor to tweak the post? This will help.
Download and install the WP-Markdown plugin.
Navigate to Settings->Writing.
Configure your settings. If you would like to allow comments in markdown, you can do that as well.
Using WP-Markdown is a full commitment. Once you enable it, the WYSIWYG editor is no longer available.
This is great for me because I found the stock editor to be cumbersome, and doing things in HTML is arduous.
To make it a bit easier, a preview of the rendered text is available below the markdown editor text field.
Have fun crafting in a new language!