This answer on the question about submitting community ads on other (graduated) Stack Exchange sites suggests promoting individual questions:
We can probably get away with something non-picturey (it's a word now...). I have seen several for UX.SE that are very simple. I can't find their recent ads on their Meta, but some of their older ones, here, are just boiled down versions of their questions with links back to the relevant question.
That's a great idea. (Thanks Andy!) So, which specific questions from our site should we advertise on other sites? Questions should be well-written and relevant to the target community and ideally should have at least one good answer.
Please post one suggestion per answer, linking to the question and saying what site(s) we should submit it to.