Been playing with XSLT a bit recently. It is quite a
nice transformation language. I have been porting the gtk-doc
DocBook -> HTML conversion program
to use xsltproc (with
a customisation layer over Norman Walsh’s XSL stylesheets),
rather than Jade (with a customisation layer over his DSSSL
stylesheets). Took a little while to learn what I needed,
but the end result looked fairly elegant.

While working on the customisation layer, I even found a
simple bug
in the base stylesheets.