Generally speaking, the current forums covers a large variety of topics - more than enough in my opinion. Of course, more will become available with the introduction of new Apple products & services. Now to specifically answer the question, no, there aren't any forum topics I'd like to see that aren't already available.
How about a section for Beta software? This is an issue close to my heart, as recently received an 'iMore infraction' for posting in the App/Software section about World of Tanks Blitz beta signup, and would mean less work for Moderators, so they can spend more time starting threads.