Industrial Light & Magic have released a VFX breakdown of their superb work done for Pacific Rim.
Behind the Magic: Building a Digital New York for The Avengers
ILM go into more detail on how they recreated New York for The Avengers.
Behind the Magic: The Visual Effects of The Avengers
ILM have put together an awesome behind the scenes featurette for The Avengers.
Behind the Magic: Marvel's The Avengers - Anatomy of a Shot
ILM go in-depth on one of the most impressive and challenging VFX sequence from The Avengers.