What's going to happen in Thor's credit scene?

I myself thing its going to involve Chris O'Dowd (The only actor who has yet to be given a specific role) whose role was apparently all in Post Production. I also think it will involve teasing for either Guardians, or Doctor Strange

guardians

Chris O'Dowd is simply a a special guest, so he says, he has one date scene with Natalie Portman's character, Jane Foster. However, this would not be the first time marvel has attempted to lead us astray.

http://moviepilot.com/stories/897409-thor-has-competition-chris-o-dowd-will-date-natalie-portman-in-thor-2

Batman and Superman.

I'm hoping it's Dr. Strange. The whole darkness thing is right up his alley.

Spider-Man

Thanos twatting in private (or whatever that thing with the ass is called).