Hello,
I've finally sent what I have from the Xml module. Don't expect too much 
from it, it's in an initial state, with not much functionality. Currently 
it can extract the tags contents, but the attributes are in the TODO list.
I hope you get the idea on how it works. There's a list of the tag types, 
and there's a custom function (callbacks) for handling each tag type's 
translation. Modifying this tag types list you and writing the custom 
handling functions you can treat (I hope) each possible XML derivate 
format (even some non-XML formats). The documentation should clear it a 
little more.
I attach an adaptation of the Dia module and a sample Docbook module that 
work both with the Xml module. The new Dia module is fully functional (I 
like those really simple formats ;), but the Docbook one is only for 
testing. At least those are examples of how simple the derived modules can 
be.
Comments, patches, ideas, etc... are welcome.
Regards,
Jordi Vilalta