Tekstilo is a word processor for Mac OS X (and eventually GNUStep). It is designed to correspond to the WYSIWYM philosophy (What you see is what you mean).
The Writers Forge is a fiction authoring suite, an IDE for writers. The tool suite will provide integrated support for writing screenplays and prose, and developing plot and character. The backend will support many target formats, including XML and PDF.
Alpaca is a programmable rich-text editor for authors using Mac OS X. It is built on, and programmable in, Common Lisp, and has a complete Common Lisp programming environment built into it.
PowerMaker will be a fully developed Text/Word Processor and Presentation/Slide Manager for MacOS X. Name comes from two commercial Apps it tries to resemble and mix in look and feel as good as possible: PowerPoint by Microsoft & FrameMaker by Adobe