To my mind, the killer feature of Google Docs is not that it is Web-based, per se. It's that it makes real-time collaboration easy. You can invite a user into a document you currently have open, and you both can edit the file at the same time. It's not a feature you're going to need all the time, but when you're on a deadline and need to get sign-off from one or more other person on a document right away, it's a life-saver (see also: Zooos).
Fighting this killer feature is Microsoft Word's own … Read more