I see a lot of text-editing environments geared towards "distraction-free, focused editing" but not a lot of innovation on an OS focused on the same experience. I would like to see such a "writing OS" that boots to a text editor in less than a second. Maybe this OS is a candidate?
But it's not a practically usable OS, it's more like a study in how far you can get with pure assembly. Though if a text editor is really all you want, it might be good enough.