You can also upload a Word (or whatever) document directly from your computer from inside Google Docs.

Before I discovered Google Docs, I typed all my WIPs right into a Gmail draft document and kept them all in my drafts folder. That way I could even give them color-coded labels that show up in my gmail folder. For finishing a document, though, or writing drabbles, I use Google Docs because it has the word count feature.

It has worked well for me because I seem to lose my hard drive every so often, and pretty often I need to access stuff from computers that aren't mine.