ACS just set it up, and already has 76 topics.
This is an excellent idea; I hope that people continue contributing topics, and that students use the topics. I tried something similar several years ago, and found it quite hard to get good submissions. But I wish ACS all the best with this, and commend them on trying (and, with the first batch of submissions, succeeding).
So please submit topics if you have some to recommend, and search or browse for topics if you're looking for something to write about. Naturally, the topics will largely end up being focused largely on those matters that interest ACS's largely liberal constituency, but that strikes me as perfectly fine.