Google Docs Rocks

Now this is one application I think is really useful. It makes sense to store one document on the internet rather than emailing numerous copies and trying to keep track of which version it is. It would be especially useful in the work place when compiling newsletters or when several people are working on the one document. I'm not quite sure how this differs from a wiki though where you can provide certain people with an invite key. Except maybe a wiki is more of a web page whilst google docs is just for documents?