Nathan Kontny is working on a collaborative text editor:
Draft is a distraction free editor that auto-saves as you type. But as you go along, you can mark major versions of your work […]
When you share your document, any changes your collaborator makes are on their own copy of the document, and you get to accept or ignore each individual change they make.
Enough with “distraction free” already, but the rest of his project sounds interesting.
There are surprisingly few simple options out there for collaborative writing, so I’m always excited when someone comes along and tries to crack that nut.