I wrote a plugin about a year ago that allows multiple users to edit a confluence page at once. The pluging breaks a page down into sections (automatically) and offers in-place editing.
I personally think confluence would be much neater if users didn't have to navigate away from a page to edit it. It's something I wrote in my spare time but I suspect some people may find it a little interesting.
For a sneak preview you can see what I put on my blog.