"The Avengers" animatics supervisor Federico D'Alessandro has posted online several videos of storyboarded scenes that didn't make in into the finished 2012 film.
Most of the scenes revolve around "Iron Man," but one shows that the character of Janet Van Dyne, a.k.a. The Wasp, actually made it pretty far along in the production process. It seems that iconic shot from all the trailers that pans around the entire team originally included Wasp.
Whedon reportedly wanted the character in the film but had to cut her out due to there being too many characters already. The character's first appearance will now likely take place during Edgar Wright's "Ant-Man" film.
Other scenes include Iron Man taking on bad guys, an alternate version of Loki's escape, and and extended version of the Stark and Loki fight.