We have had the ability to publish an Excel Workbook to the web before but we needed to have either SharePoint or save the file as an HTML page and then post. Now with the Office Web Apps you can publish your Workbook to the web in either your website or a blog entry like this one. The advantage of this method is that when you update the data in the workbook it automatically updates the webpage that is displaying the workbook.
It might not be needed for everything but I think it is kind of cool.
Follow this link to get the directions on how to do this. You can also do this with PowerPoint.
