I'm currently working on XWiki's answer to the French government call for Web 2.0 projects. We started a fresh XWiki Enterprise 1.9 instance to work together on our answer and I love using it:
- Full-screen edition allows me to focus on what I'm writing
- The Alt+Caps+S shortcut lets me save my modifications without reloading the page
- I can create links easily thus keeping the whole thing organized
- It's WYSIWYG so I don't need to worry about the syntax
Basically, it combines all the advantages of traditional desktop-based text editors with those of a wiki :-)