I was watching The Avengers last night (26th April 2015) on 7Mate on Australian Television. When I first saw the film in the theater I didn't know who Thanos was or the meaning behind the post-credits scene, but now knowing I was expecting to see it in a new light.
After the credits however there was a different scene. The Avengers (including Thor) were in a restaurant, possibly in New York given its state, eating burgers... that's it. No Thanos, no dialogue, no nothing.
Then I remembered Iron Man 3; post-credits I was expecting maybe a hint of Ultron, however it was just Tony lounging back as if he was having a therapy session (he interrupts the guy who tried to explain he wasn't a therapist).
This got me wondering, do all the Marvel Films have a second post-credit scene which doesn't have any hints to future films? If so, why even have it in there?