The title of this might be a little weird, but I can't think of a good title. The idea, is for a way to say effectively "Show me the articles that are both in Category A and Category B". Currently, this is possible with DPL, but it's not possible if you want to just link somebody this on the fly.
Topic on Project:WikiProject Extensions/Ideas
This is doable if you use CirrusSearch - search for:
deepcat:"Used on Wikimedia" deepcat:"All skins"
You can then link to the search page.