My XSLT experience is fairly light so I'm keen to find out about real world applications. In the original poster's code he would encounter an element like this:

<child id="2">435</child>
[download]

At this point his code would then (recursively) parse down into the file called '435.xml'. I realise recursive processing is no problem for XSLT, but how would you load in another file and process it?