First a tool with a cost, followed by a free tip/trick.
Word Cleaner: "Welcome to the easy way to convert word documents to HTML/XHTML and automatically clean up the code! Word Cleaner is the perfect tool for web designers and people who have to maintain web sites. Word Cleaner will save you hours spent tediously converting Word (and .rtf & .txt) files to HTML/XHTML and cleaning them by hand. You can also clean up existing html files. Best of all our powerful templates enable you to create processes that automate your document conversion and cleaning."
Word-to-HTML for FREE: This trick is from Madeline Koch, a colleague in my Editor's Association of Canada. "Here's a nice and easy trick. Email the Word file to your gmail account. It will give you an option to open up the attachment in a browser window, and you then ask your browser to show the source code -- copy and paste it into your html editor, tweak it as needed and presto! A web page. Hugely grateful for whoever told me this trick!"