To the XSLT which transforms my RDF (FOAF) file into XHTML, I added microformat attributes (class="fn", class="url" and rel="me"). Use a "view generated source" bookmarklet to see them.
It seemed like a good idea, although it's not possible to point an extractor like X2V at the XSL-transformed version of an RDF/XML file: it just gets the original (though maybe the extractor could be altered to import any additional transforms specified by the original file?). Greasemonkey scripts and bookmarklets will be able to get at the data anyway.