Ability to use Markdown instead of TinyMCE

I have a number of problems with TinyMCE, which are just problems I run into on all attempts at a web WYSIWYG editor:

• pasting from somewhere else retains formatting which you have to go to HTML mode to remove
• entering text requires tinkering with toolbar buttons instead of typing naturally

I would like an option to not use it, but instead use a normal text area with Markdown formatting + Wiki link/embedding applied at render-time.

Presumably others would be used to other Wiki engines, so it might be generalisable to allow multiple kinds of configurable filtering, but really the only one I find natural to enter is Markdown.