Besides many of those already mentioned, I'd like to see re-releases of:

Flash Gordon (there's already some decent non-R1 versions)
The Great Escape (like the great R2 SE)
Spaceballs (not a bad disc, but not that great either)

Bladerunner - Better transfer + supplemental material.
The Abyss - Anamorphic
Heat - Better transfer + DTS + supplemental material
The Crow - Alex Proyas Commentary track
The Thin Red Line - more supplemental material

I would like to see anamorphic versions of...

Nightmare Before Christmas
Sling Blade
Office Space

If you have region free capability you could always buy the Danish (R2) version which is anamorphic.

I didn't know that. thanks.

Off the top of my head, and sticking to things that haven't been announced or rumored already:

The Graduate
Grosse Pointe Blank
Heat
Superman II

I'd throw in Beautiful Girls but since the unfortunate death of Ted Demme I'm not sure if that would even be possible.

I'd settle for the first two Batman movies...you can keep the rest! :)

As for the other two above, I'm pretty sure they're slated for re-release next year (although Adaptation won't be a Criterion title, there was an upcoming "Special Edition DVD" trailer on this awesome disc).

In addition to a lot of the stuff already mentioned:

The Jerk
Frantic
Christine
Mean Streets
It's A Wonderful Life
The Deer Hunter
Predator

And this stuff i don't know if it's ever been on dvd:
Cocoon
Trapped In Paradise
Fire In The Sky
First Born
Radio Flyer

Titles that are currently OOP:

The Universal Classic Horror films (The Mummy, The Invisible Man, etc...)
The Paramount Marx Brothers films (Duck Soup, Horsefeathers, etc...)
The Sam Goldwyn Collection (Ball of Fire, The Princess and the Pirate, etc...)

Titles that are currently in print but with MAR:

Arthur
Bank Shot
Grumpy/Grumpier Old Men
Happy Gilmore
New York Stories

I just saw Quiz Show last night. It's a great movie but the DVD only has the trailer. I'd love to see a special edition, but obtaining some of the original footage might be impossible. It would also be interesting to interview the people involved in the scandal but I'm sure most of them wouldn't want to talk.