I could suggest my staples, but what would YOU guys want me to talk about?
Keep in mind, I only feel comfortable about subject matter I actually KNOW, but that hasn't stopped me in the past. I once hosted a panel on Heinlein, and I hadn't actually read any books of his since high school, and I didn't like what I read. So I sat up there and challenged anyone to know more than me about Heinlein than me to come up and prove it. And they did. I didn't have to do anything but moderate and ask random questions to my new panelists.
They don't call 'em "cons" for nothin'... :)