Daredevil apparently showed the villainous Bullseye stuck in a body cast after the credits (and I’m not sure I stuck around for that), and then — I think — our recent sense of post-credits entitlement really began with the bit at the end of X-Men: The Last Stand (two years prior to Iron Man) that revealed Prof. X is still alive. (Sidenote: In reading about that teaser, I have only just learned that the new body into which he transferred his mind in that scene is supposed to be the twin whose mind he accidentally wiped out back when they were in the womb — meaning that the character is essentially Cassandra Nova, for the Grant Morrison fans out there, albeit a male Cassandra Nova. Since the male body is at Moira’s facility in Scotland, perhaps we should henceforth refer to it as Cassandra Nova Scotia. Ha!)
What the online accounts about post-credits sequences I read left out, though, was that the expectation that the post-credits bit will be something important rather than just a joke was probably created in 2002 by the widely-advertised alternate ending of the zombie movie 28 Days Later. So, chronologically/causally, roughly: Muppets > ninjas > zombies > pirates > mutants > Robert Downey Jr., and the rest is…uh, contemporaneous.
How will next year’s Thor movie tease next year’s Captain America movie, though, that is the question. Maybe it would be easier for both films to tease 2012’s scheduled Avengers movie. To which I can only say: Avengers ensemble!