Finally, iA Writer for Mac OS got released and is available in the App Store now. iA Writer on the iPad is by far my favourite writing solution and the Mac version features similar features plus Markdown (yay) integration.
Perfect someone who prefers to use the keyboard instead of mouse clicks.
More information you can find on the iA Writer website.
For some reason I’m missing (or not finding) an obvious way to export directly to HTML, but maybe that’s just me. NValt does the trick for now.