I always thought that would be a cool idea, having the option of watching the commentary with picture in picture or something... especially on Shaun of the Dead with the actors were they seem to be more concerned with drinking tea and wine and eating cakes! Funny!
I should have mentioned the Thing too! One of my favourite movies. I love the Commentary with Carpenter and Russell, Carpenter smokes and rasps his way through and russell just laughs. Great extras, you really get to appreciate the production design, which is still among the best I've seen. And I love the story about the Wolf.
I liked Kevin Smiths lecture DVD, forget the name, not an extra either, but it's funny, especially his stories about Prince (Very strange) and the producer of Superman who has this thing about Spiders!
Someone mentioned the Batman Begins disc, that was very disappointing and I was sure there would be a Special Addition at some stage. But alas no, just went into the bargain bins. Shame.
Some more cool ones
This is England:
A cool look into the method of the Indy Genius that is Shane Meadows.
Lost in Translation:
Access all areas Documentary for another low budget guerilla style shoot.
Reseveoir Dogs (Special Addition):
Great interviews with the cast. Fascinating insights and anecdotes. Cool look at the preproduction. Tarantino gives a great recount of his disastrous Sundance screenings and there's a great Documentary about Film Noir.
All the ghibli films come with a storyboard comparison, which is great because they're drawn be Myazaki himself. But this has a nice documentary and a look inside Studio Ghibli, the greatest animation studio in the world, which is a surprisingly small and unstated place.
The Dark Crystal:
Fascinating behind the scenes Documentary and look at a true Genius at work, Jim Henson.