I've gone through the tutorials on how to create a custom ribbon with Visual Studio. I see that you can export your Ribbon XML. Is it possible to utilize this ribbon with another document? Do you have to use Visual Studio at that point or is there a way to embed the custom ribbons into another document? (without VSTO)
Ok... After doing more and more digging. I've come up with some answers.
You do NOT need to do a full-blown VSTO (Visual Studio 2008/2010) Office document to modify the Ribbon (Fluent UI). You can create custom XML (which is real easy if you use the Ribbon designer in Visual Studio) and inject it into the Office document. To make it real simple there is a tool out there that does this for you: Custom UI Editor for Microsoft Office.
Also there are great references on this site: http://www.rondebruin.nl/ for instance: http://www.rondebruin.nl/ribbonx20072010.htm