David Warnock posted about trials he'll be making in a hymn XML microformat.
I think I'll look deeper in the Theological Markup Language (ThML) hymns option, founded and championed by the folks at the Christian Classics Ethereal Library. It looks a bit more robust, even though Br. Warnock has ideas so well digested that I don't understand them!
Here are, for instance, Watt's hymns in ThML.