Food for thought: When I.E. renders vanilla XML it does so with its own XSL stylesheet - res://msxml(1|2|3).dll/defaultss.xsl. This makes all child nodes appear as nice collapsible DHTML layers. So, for Domino Categorised-View XML like this you could tailor this XSL to create a nice DHTML version of a categorised view. Hence: your own twisty images, no need to refresh page, open categories remain open as you open others etc etc. One day I might get round to doing this... the problem with the above XML is that response documents aren't actually child nodes in the XML. Why, why, why ....?

Getting to know XSLT is actually really interesting. I had made the mistake of thinking there wasn't much to it, just some "simple" pattern matching. It is of course a language in its own right. A few resources. Articles on their way on soon(ish).