Prospero's Books
Shaun of the Dead
Tenebrae
Moulin Rouge
Brazil
Dune
Raiders of the Lost Ark
Legend
The Devils
Titanic

I never get tired of these (a few more than 10, can't resist):

Goodfellas
Oldboy
Jaws
ALIEN
A Christmas Story
Halloween
The Thing (Carpenter)
Fight Club
Spinal Tap
Blues Brothers
Animal House
Monty Python and the Holy Grail
ReAnimator (the longer, R rated cut)

Off the top of my head:

Shaun of the Dead
Serenity
Pulp Fiction
Jackie Brown
Reservoir Dogs (just about anything Tarantino)
Alien
Aliens
Underworld Evolution
Star Trek II
The Devil's Rejects
Blade II

Arthur
Auntie Mame
Death Becomes Her
Hannah and Her Sisters
Hedwig and the Angry Inch
Psycho Beach Party
The Royal Tenenbaums
Sleepy Hollow
Sordid Lives
Torch Song Trilogy

The Godfather: Part II
Heat
Casino
Raising Arizona
Goodfellas
Fight Club
The Road To Perdition
The Incredibles
Sleeping Beauty
The Iron Giant

Alien
Aliens
Ghost and The Darkness (not so much anymore since buying a 40" LCD)
From Dusk Till Dawn
Jurassic Park
Frankenstein (Original)
Total Recall
Night of The Living Dead
Dawn of the Dead
Jaws
Evil Dead II

Wow, didn't pick one classic "classic" like BenHur, but if you were dropping me on a Desert Island with a Portable DVD Player those are the ones I'd take. Humm, sounds like the makings of a Twilight Zone episode. I reach for the DVD Player and find I have no batteries................it's not fair...waaaaaah

Goodfellas
Casino
A Bronx Tale
Scum
Football Factory
What Becomes of the broken hearted
Half Baked
Stand By Me
Lock stock

in no particular order

bladerunner
wizard of oz
eternal sunshine of the spotless mind
vanilla sky
M*A*S*H
full metal jacket
a midnight clear
rushmore
amelie
unbreakable

i'm sure there are others i have not thought of yet.

Alien in 30 seconds, re-enacted by bunnies
The Exorcist in 30 seconds, re-enacted by bunnies
Jaws in 30 seconds, re-enacted by bunnies
Pulp Fiction in 30 seconds, re-enacted by bunnies
Titanic in 30 seconds, re-enacted by bunnies
Raiders of the Lost Ark in 30 seconds, re-enacted by bunnies
Fight Club in 30 seconds, re-enacted by bunnies
King Kong in 30 seconds, re-enacted by bunnies
Casablanca in 30 seconds, re-enacted by bunnies
Star Wars in 30 seconds, re-enacted by bunnies

1. Dazed and Confused
2. Rounders
3. Good Will Hunting
4. Swingers
5. Beautiful Girls
6. Fight Club
7. Billy Madison
8. Happy Gilmore
9. Gone In Sixty Seconds
10. Half Baked

Rules of the Game
Chungking Express
Satantango
My Life To Live
Ocean's 11
Ocean's 12
Au Hasard Balthazar
Three Colors Red
Cache
Miller's Crossing

Rocky IV
White Water Summer
Rad
Ghost
Ransom (1996)
The Last American Virgin
Forrest Gump
Terminator 2
Sling Blade
Porky's

Goodfellas
True Romance
From Dusk 'til Dawn
Texas Chainsaw Massacre '74
American Psycho
Breakfast Club
Evil Dead 2
Die Hard
Predator
Hard Boiled
The Replacement Killers

I don't want to use the term "obsession" too strong of a word, but I like these movies very much:

Dog Day Afternoon
One Flew Over The Cuckoo's Nest
Gloria (1980) Hated the remake starring Sharon Stone.
The Wizard of Oz
Pee Wee's Big Adventure
Body Double
Independence Day
Toy Story 1&2
The Passion of the Christ
Ghost
The Lost Boys
The Elephant Man
King Kong (2005)
Scarface (1980)
The Bad Seed (1956)
What Ever Happen To Baby Jane
Homicidal
Mildred Pierce
Kramer vs Kramer
House of Sand and Fog
The Ten Commandments
Lord of Illusions
Jesus of Nazareth
Full Metal Jacket
Lady Sings the Blues
Valley of the Dolls
I Want to Live (1958)
Raging Bull
Mommie Dearest
Nightbreed
Basic Instinct
Con Air
The Lion King
Enemy of the State
Snow White and the Seven Dwarfs
The Iron Giant, and many more.

Willy Wonka & the Chocolate Factory.
the Star Wars Trilogy.
Indiana Jones Trilogy.
Superman.
True Romance.
E.T.
Grease.
the Jerk.
Pick a Pixar flick.
Caddyshack.

Just off the top of my head.

West Side Story
Angels with Dirty Faces
Pale Rider
Rounders
Jesus Christ Superstar
Can't Buy Me Love
Duck Soup
Cool Hand Luke
It's a Mad Mad Mad Mad World
The Karate Kid

I've seen all of the above many many times each.

I presume obsessed as meaning watch over and over while remaining entertained and finding new meanings and inflections. Or whatever. Mine:

Rushmore
The Thing (Carpenter)
Excalibur
Sorcerer
The Exorcist
Fight Club
Alien
Kingpin
Jackie Brown
Star Trek II: The Wrath of Khan

A quick list..

1. Vertigo
2. Gattaca
3. Grosse Pointe Blank
4. Heat
5. Conan the Barbarian
6. Solaris (original and remake)
7. Groundhog Day
8. Willy Wonka and the Chocolate Factory
9. Layer Cake
10. Dirty Harry

I suppose these are the top ten films I quote the most often, if that is any measure of film obsession:

Raiders of the Lost Ark.
Ghostbusters.
BASEketball.
The Big Lebowski.
Rushmore.
LotR: Fellowship of the Ring.
The Blues Brothers.
Shaun of the Dead.
Clue.
Back to the Future trilogy.

Dawn of the Dead (78)
Before Sunrise/Sunset
Mulholland Drive
Blue Velvet
Star Wars (all of them)
The Cabinet of Dr. Caligari
A Clockwork Orange
Buffalo '66
The 400 Blows
The Rules of Attraction

For whatever reason I find myself never getting tired of watching these movie
13th Warrior
Groundhog day
True Romance
Gattaca
Conan
Ghostbusters
Hard Boiled
Dazed and Confused
Shaun of the Dead

Shaun of the Dead.

I had that dvd in my player for months and I can't think of anything boarder line close to that.

Mulholland Drive
Shaun of the Dead
Oldboy
Audition
Dark City
Fight Club
City of Lost Children
Donnie Darko
Requiem for a Dream
Beetlejuice/Run Lola Run

Right now ... The Departed, The Departed and The Departed. I've read countless reviews and discussion boards about this movie just to relive my experience of it.

01: Yankee Doodle Dandy
This film. Boy oh boy - I saw it for the first time on the Fourth of July, 2006 on TCM, and I was hooked. The film has never been out of my mind since then, and when I'm not watching this beautifully acted and flag-waving spectacle with James Cagney, I'm listening to the awesome soundtrack on my way to work. What an impact this film had on me, and its spread throughout my family. My 3-year old son has learned the words to Over There already, and was also listening to the soundtrack in the car with his mother.

02: My Cousin Vinny
This film is more than just a comedy. It is so deep - from Vinny (Joe Pesci) being "ascared" of blowing the case; to the great acting job delivered by Fred Gwynne as Judge Haller; and, of course, the comedy.

03:Titanic (1953)
I like the majority of adaptions about the ill-fated ocean liner, but this one is my favorite. The redemptive qualities of Sturges at the end of the film brought it all home to me. People can change.

04: A Few Good Men
The acting all around, from Jack Nicholson to Kevin Bacon, is superb. Great story, from start to finish.

05: Memento
Guy Pearce proved that he could carry a movie, and did he ever. And whoever said the suit makes the man didn't know what he was talking about! Its the man that makes the suit, and let me tell you why. Throughout the movie, Leonard (Pearce) is wearing a very expensive suit that doesn't belong to him (as we find out later), and it looks great on him, and he looks great in it. Once the same suit is worn by the original owner towards the end of the film, both the suit and the guy wearing it look like shit.

06: L.A. Confidential
Not only did this film have the great Guy Pearce, but it sported one of the best ensembles to grace a motion picture: Russell Crowe, Kevin Spacey, and James Cromwell. This film proved the point that even the smartest person can be very naive about their own selves when thrown into tough situations. People's morals and beliefs can be shattered, as we see with the character Ed Exley (Pearce).

07: Fargo
I never tire of this film. At first, I thought it was a broad comedy with the accents they were sporting, but then I realized that they were being "real," and people actually talk that way in some parts of this country (how this can be one country is beyond me after watching this). William H. Macy "made" this picture for me - his utter desperation and frustration was real - I felt it, and I don't think I've ever seen that kind of brilliant acting before or since.

08: Its A Wonderful Life
My reasons for loving this particular film is probably the same reason why everybody loves this particular film (and it ain't because we see an older Alfalfa in it, neither). George Bailey (James Stewart) has lived his whole life pleasing other people before pleasing himself, and he gets to a point where he can't please them (or himself) anymore, and wants to kill himself. A grand holiday picture for the entire family.

09: The Hustler
One word: Jackie Gleason. This movie and its director was very smart - they brought in Gleason's character, Minnesota Fats, at the very beginning of the picture, and then at the very end of the picture. We're book-ended with Gleason, and how sweet it is!

10: The Godfather
I could watch this movie over and over and over again (and I have, too). I'm a sucker for people who change their morals in times of crisis, and this film tops them all. Michael Corleone (Al Pacino) goes from being a nice, innocent kid affectionally nick-named "Mikey" by his older brothers, and is transformed into a cold-blooded killer in order to protect his father and his family (or Family, as it were). I love James Caan in this picture, too, based on the fact that his character Sonny Corleone is a hot-headed, violent guy who cheats on his wife any chance he gets, yet we feel something for him when he gets gunned down on the causeway.

Well, these are 10 films that I truly love, but they're not the only ones.