This feature request is specifically about the Semantic Drilldown extension.
Would it be possible to use the Special:BrowseData page as a format for semantic inline queries? What I might like to see, for instance, would be a new option for the "format" parameter, such as "drilldown." It would then need one of two additional special parameters, such as "filtercat" and "filters." For filtercat, one would enter a top-level Category name, and the search query would use the filters on that Category page to filter the search results. Or for filters, one would enter a filter or comma-separated list of filters to use to filter the results.
I really like the Drilldown interface, and I'm looking to expand its functionality on my wiki. :)