Example markdown doc from msdn async programming C#,
While blogging using markdown on wordpress adam P's Markdown Cheatsheet is handy.
Here are few online tools available directly for editing in markdown syntax,
blogifier now has markdown as default editor, try a demo!
wordpress recently added the feature of enabling markdown syntax for writing. This is pretty neat. wordpress.com - support provides instruction how to enable the feature. They also provide a Markdown quick reference
However, if you are writing scientific equations you can find troubles.
Saliya's Blogs - Blogging with Markdown in Blogger shows how to do this in blogger.
pandoc allows viewing wiki syntax differences along with markdown.
Projects on github, simplemde-markdown-editor
stackexchange's C# markdown, Which Markdown library is used? ref