This was something that came up recently in the homotopy theory chat room. Even if it wasn't to homotopy theory, has MO ever considered asking active users with interesting research to host lectures or seminars in chat rooms specifically for this purpose? They could of course be in rooms where only perhaps a few people had speaking privileges, or something along those lines, to prevent everyone from just talking incessantly. One benefit of this also would be that even people who aren't on MO could lurk and possibly learn something.
Has anyone considered this before?