I think it could be useful to consider some ways in which v.nu reporting of obsolete markup could be improved -- for example, handiing/reporting obsolete attributes, not just obsolete elements.

Another kind of simple enhancement that could be made is that instead of just reporting that a particular element or attribute is obsolete, some simple advice/suggestions stuff could be emitted; for example, the report for the "center" element could say something like, "The center element is obsolete; use CSS for styling instead."