Journal Writer (calls itself SJournal) is what it's name suggests. I use it for writing a daily Journal. It uses markup.

When you start JournalWriter it creates a file (edit it's path in the JournalWriter.exe.config) for your daily journal and adds room for the first day. Double click into the editor windows on the right and edit your text.

There's also a description of the markdown capabilities of Journal Writer under the help menu.