Derrick Story has a nifty tip for using GMail to convert Word docs to HTML. Just send it as an attachment to your GMail account and then select "View as HTML" next to the attachment. I just tried it with this Word doc and got this HTML document. Very nice.
Now, if someone would just get around to building a tool that you drag a Word doc onto and it uses GMail to convert it to HTML and deposit the result in the same directory, that would be awesome.