Well we'd need a better developed Theory of Fun to quantitatively answer that. How about, "a lot"?

ETA: and there's so much talk because Eliezer resumed posting new chapters (and a new arc) a couple of weeks ago after a long hiatus. And the new chapters have already set up a very dangerous situation and all end in cliffhangers and Eliezer added notes asking people to try to out-think Harry in solving the crisis before the next chapter is out. Which resulted in a lot of theories and suggestions being posted.