Another web-based outliner that allows sharing is Loose Stitch at http://loosestitch.com/

From its web site:

"Create outlines for whatever you want...
Essay Writing
Presentation Notes
Cooking Recipes
Sitemaps for web designers. We use it extensively for this
Functional Requirement Documents
Organising your ideas
Managing your Todos & Tasks
... and anything else you wish to keep track of"

Daly