I really enjoyed the special features set on the second blu-ray disk for Iron Man.
Seeing how much energy from so many people is required to create something of this quality and refinement. I would love to be part of a smaller production at some point to get a feel for the process.
I love seeing the development of things like the various HUDs and their character. Getting a greater understanding and appreciation for a sub-element like this shows us how complex a full movie of this calibre really is. There is a cool coverage of the HUD and POV graphics in the article on the User Interface Resource Center. I like the way there is quite a developed logic to the design that only flashes up there, that it is still quite resolved and indeed evolves through the movie shows their dedication to delivering a refined Iron Man experience for us.
This vid shows off the MkII HUD through the flight test sequence: