For Transformers, augmented reality allowed us to wear Optimus Prime's head. For Iron Man 2, the shamefully enjoyable promotion gets better: You can now wear the mask, see yourself in Stark's HUD and record it. Go forth and daydream.
UPDATE: Just got done testing it here - my experience wasn't QUITE as smooth as the video! The first time you visit the site, expect some serious download/configuration times. And if anyone is able to get a silky smooth framerate, well, your computer obviously isn't as old as mine.