Although Microsoft is not happy about it, much of the world has been moving in the direction of the XML-based OpenDocument format, otherwise known by it's much longer, full name: the OASIS Open Document Format for Office Applications.
This opens up new possibilities for document generation and allows the creation of all sorts of Office-type documents using only a text editor (assuming you know what you're doing). A number of applications, including OpenOffice, already support the OpenDocument format. Microsoft Office does not, but there are plugins available.