Lots of your topics seem to require a degree of depth in the knowledge of a language to properly discuss (without dumbing it down too much). If this is not a problem, I would recommend discussion about Bitcoin regarding its technology (perhaps something with scalability).
Far too many individuals have an uninformed perspective on how the system functions/should function (i.e. free transactions, larger block size, how mining works, etc.) and I believe that it is critical to make some of the knowledge more widespread. I have seen far too many people ask how signing a message works, what a node is, etc. (on this forum, no less)
Once 5 threads have been started, then I will open a poll for the community to decide which one is the best, and the winner will receive an additional 25 merits.
Poll can be spoil by bots that's why I think that the winner should be chosen by trusted members.
That, or replies to a central thread would work. Have it self-modded to disincentivize spam.