One of the interesting aspects of entertainment (TV, Video Games, etc.) has been the discussion of them with other people. As watching of episodic content becomes less synchronized (due to DVRs, Netflix, and even to some extent regional/time-zone-based release dates), this is harder to do without spoilers for people.
So, I think it’d be neat to have Internet forums for such media have a feature where each user put in how far along they were in the series/episode/game/whatever, and only saw the posts done by others when they said they were up to the point. That is, the time basis for the forum is however far along in the plot one is, and so you can have “interactive” discussions with others who are at the same point, even when you’re actually experiencing the forum at quite different times.
I don’t know how well it’d work in practice, or if things like this exist already somewhere, but I wanted to put the idea out there while I was thinking of it.