[Population: One] <A HREF="http://popone.innocence.com/ar

Although Ulysses has flaws, CopyWrite has a very similar interface and provides a slightly better editing pane (paragraph spacing) plus in-line formatting. It looks like I can coerce InDesign into handling formatting codes for me, which means named styles are less important. And CopyWrite is about a quarter the price of Ulysses.

I'm doing my latest game (The Kiss of God) in CopyWrite; after I'm done I'll post about the experience.