The first trailer has been released for X-Men: Days of Future Past.
X-Men: First Class - New Trailer
If you don't mind the Russian translation, there's a new trailer for X-Men: First Class, with a lot of new footage.
Guardians of the Galaxy - Trailer + Featurette
Marvel have released a new trailer and a featurette for Guardians of the Galaxy.
The Avengers - Wild Ride Featurette
The cast and crew of The Avengers talk about the unprecedented scale of the film.