I couldn't find anything of the sort, so I thought I'd start one, in case those of you look for stuff like this. Recently, I just found out that the US release of Chariots of Fire does NOT have the isolated music track that the UK and Japenese releases do. Also, blu-ray.com just posted a review of Bound, which is missing the DTS-HD 5.1 track that the French release has. Know of any others? I'm starting to do more researching now on titles, rather than just jumping in and buying them, especially for those I've really been wanting. I'm trying to see releases that are missing content, not so much steelbooks or anything like that. So here are the couple of US releases missing stuff:

Chariots of Fire - missing isolated music track (on UK release)
Bound - missing English DTS-HD 5.1 track (on French release)

The Devil Wears Prada UK - All extras from the DVD but missing the trivia track from other Region releases.

The Thing (1982) UK - All extras from Laserdisc and DVD, US uses excerpts of the documentary for a PiP track.

Man on Fire UK - All extras from the DVD.

Sorry, meant features on only blu rays from other regions only. I think DVD/laserdisc/VHS, etc would make this too damn big. And there's a recent VHS one that's now started.

Drag Me to Hell is missing 'Interviews with Sam Raimi, Alison Lohman and Justin Long' from UK BD

Apparently the new Bound BD is missing several extras from the French release.

Perusing my collection of non-Region A releases:

Manhunter release is missing the following from its UK BD counterpart:
- Michael Mann audio commentary
- Director's cut
- Two making-of featurettes
- Theatrical trailer

Mean Streets is missing the following from its French BD counterpart:
- Audio interview with Martin Scorsese
- Scorsese's documentary Italianamerican (in HD)
- Making-of featurette
- Interview with the film's cinematographer
- Analysis by film critic Kent Jones
- Opening credits/home movie outtakes

Time Bandits is missing the following from its UK BD counterpart:
- Time Bandits Scrapbook (from the Criterion DVD/LD, I believe)
- A video transfer that doesn't look like complete ass

Dawn of the Dead is missing the following from its UK BD counterpart:
- Director's cut and Argento's cut (SD only)
- Additional audio commentary by producer Richard Rubenstein
- Document of the Dead documentary plus outtakes/deleted scenes from Document
- Fan of the Dead documentary
- Scream Greats: Tom Savini documentary

Miami Vice is missing the following from its UK counterpart:
- Theatrical cut (though I think this is available on the HD-DVD release)

LATE EDIT: The Thing (1982) is technically "missing" the following from its UK counterpart:
- All of the supplemental video features from the DVD/HD-DVD, which are severely cut up to fit in the "U-Control" feature on the US Blu. The UK BD skips U-Control and instead has all of the bonus features proper.

The UK disc of Kung Fu Hustle has the original cut of the movie on it, the US BR release only has the edited American cut.

The Bean movie blu-ray from the UK has a great set of deleted scenes with interview of Rowan Atkinson. This was only ever on the VHS of the movie years ago.

The UK release of Psycho has DTS-HD MA Mono and an Alfred Hitchcock Presents episode not found on the US Blu.

Payback UK has the theatrical cut and featurette not found on the US release.

Black Rain Japan has exclusive extras not found on the US release.

Likewise, the U.S. release of Pirate Radio is only the American theatrical cut. The UK release is the longer cut under its original title, The Boat That Rocked.

in terms of audio:

Nine (HK release: DTS-HD MA 7.1 mix / US: 5.1)
Conan the Barbarian (2011) UK release: 7.1 / US: 5.1
The Good, The Bad and the Weird (HK release: 7.1 / US: 5.1)

The US also has a 7.1. I just watched this a couple of nights ago, so it's still fresh on my mind.