Either enforce the selection of a subtopic when posting a question (and possibly expand the number of them) or do away with them. (Some topics such as Chatterbank don't need subtopics).
Currently each topic and it's subtopics are independent of each other - shouldn't selecting the topic give a list of all questions in all subtopics rather than, in effect, being just another subtopic?
e.g. with crosswords, some questions are posted in the Crosswords subtopic but most end up in the Quizzes & Puzzles topic because the poster doesn't bother selecting the subtopic, and it's not possible to see all in one list.
I suggested directly to the Spare Ed on her thread yesterday that we should be able to hover the curser over the topic list and see the sub-topic lists in those little boxes you get on some applications.