In the agile modeling literature, some have recommended using a digital camera to take photos of diagrams drawn on white boards, they also speak about throw away models

So, it didnt have to be a joke, anyway

In reply to the XML comments, you can draw a UML diagram, and save it in an XMI Xml file, I am saying, I would love to write an XMI file in Emacs, and transform it to a jpg or whatever, or view it in a graphical diagram editor.

It's a lot more practical to write XML docs, than to draw a diagram graphically in a graphical diagram editor.

Plus, if all your docs, are writen in XML (see XML publishing), you diagrams can be integrated in the rest of your docs, instead of being linked as a jpg.