As a developer in the content management industry, I see people uploading Word documents and other proprietary formats to the web all the time. This is especially true with smaller, homegrown websites that make brochures, newsletters, and forms that they want visitors to print out. The problem is that these formats aren't very web-friendly — and they're also very tacky.
A much better practice is to offer your visitors printable media in PDF format. Why? Because PDF files are portable, meaning they work just about anywhere. Most Windows users have Adobe Reader installed (a free download, if they don't have it). Mac and Linux users have software that can read PDFs which comes with their operating system. Google Docs (and thus, Gmail) has a built in PDF viewer. Even my iPhone can read PDF files!
Try doing that with a Word document, a Visio flowchart, or an AutoCAD drawing.
The important thing to realize is that you don't have to buy any expensive software to create PDF files. If you're on a Mac or a popular Linux distribution, you can usually select
File > Print and choose the PDF option. Windows users can download a free application that will give you the exact same functionality.
Once installed, CutePDF Writer will appear in your list of printers so you can quickly and easily convert any document into PDF format, which is much more reliable for the web. Using PDF files in lieu of proprietary formats will ensure that your visitors will be able to view your documents the way you intended them to — and it will give your website a more professional touch.