I just discovered the Writely project, which the Google online word processing project.
It is actually very good, providing with most of the features you are looking for in a word processing tool.
It is certainly not as good as a full-blown desktop software but provides some other features like online reviews with other users.
Other cools features are the capabilities to save to other standards formats (Word, Open Office but also PDF !)
And finally it's completely free...
