I love markdown and hate, hate, hate MS Word. For me, markdown it is a perfect way to write: concentrate in structure and content first, and style the whole thing when you are done. You forget about all the MS Word crazyness, and have a portable text that can be styled with css when published in different blogs, websites, etc. Good stuff.
I would love a text processor that allows me to write in markdown format, and apply styles to the text later, (sorta like with CSS)
Bonus points if it supports saving to .doc too.
Extra bonus points if it supports both osx and windows.