Oh, yeah, and Groundhog Day.
So you like sausage? 
Agree with many selections already mentioned. I’ll add:
Witness
We Are Marshall
Gimme Shelter
And, these bear * several* viewings, but not *many:
Being John Malkovich
Memento
House of Games
Fletch*
A few more:
Paper Moon
The Lives of Others
The Return of Martin Guerre
The Red Balloon (short feature)
These last three are foreign-language.
The Lion In Winter - one of my three Christmas “musts” along with
A Christmas Story
and
Scrooge/A Christmas Carol (the Alistair Sim version). The deliciously dysfunctional Plantagenets celebrating Christmas is probably a lot closer to reality than most Hollywood films, and is a great antidote for anyone forced to watch any of the Hallmark Channel offerings while stuck at a relative’s house for dinner. The Hepburn-O’Toole version only, please.
The Philadelphia Story
Bringing Up Baby
A Night At The Opera
Singin In The Rain
Local Hero
A Hard Day’s Night
Pride And Prejudice - the “wet Colin” version. Not strictly a movie, but who cares?
This Is Spinal Tap
Raiders Of The Lost Ark
The Adventures of Robin Hood - Flynn version only
Grand Prix - dumb story, great racing footage
The LOTR trilogy
Just remembered - Secondhand Lions.
Remembered Cabaret too.
And Pink Floyd The Wall.
Gladiator
Apollo 13
9 Reinas (Argentinian)
Groundhog Day
The Shawshank Redemption
Bridge over the River Kwai
The Power of One
The Sound of Music
The Incredibles
Groundhog Day
The Green Mile
The Shawshank Redemption
A Miracle on 34th Street (any version)
Young Frankenstein (Put the candle back!)
I’ve seen all of these at least 10 times each.
Romancing the Stone - There is no limit to how many times I can watch this movie.
I hope no one will object too strenuously if I offer my personal opinion (it’s only my opinion), but I think the Guns of Navarrone has to be heads and shoulders above most other adventure movies (both war time and peace time) including The Bridge on the River Kwai and The Eagle has Landed.
I love The Eagle has Landed (especially Donald Pleasance’s portrayal of Himmler) but The Guns of Navarrone just has all the others beat. I think that in large part, that is due to Gregory Peck’s performance. Again, it’s just my opinion, but I think he is one of the most incredibly talented actors of all time. I just love watching him work.
Bringing Up Baby
Gentlemen Prefer Blondes
Casablanca
North by Northwest
The 39 Steps
Cabaret
All That Jazz
The book was even better, as I recall. Been awhile.
Saw the movie but have yet to read the book. I agree with Lazlo. Peck (and the music) make it the thriller it is. I liked Irene Papas, too. James Darren was a little hard to take, though. 
Most of my re-watch favorites have been mentioned, but here’s my list of movies I’ve happily watched a bazillion times:
The Abyss
Beetlejuice
Groundhog Day
Last of the Mohicans
Little Shop of Horrors
O Brother Where Art Thou?
Overboard (sue me!)
The Princess Bride
The Fifth Element
Pulp Fiction
The Wizard of Oz
There are a bunch of kids’ movies that I’ve watched innumerable times because of being a mommy and all, but I find these particularly enjoyable:
Aladdin
Cars
The Emperor’s New Groove
Hercules
Mulan
Toy Story II
-
Any of the Clint Eastwood Man-with-No-Name series
Fist Full of Dollars
A Few Dollars More
The Good, the Bad, The Ugly
High Plains Drifter
Pale Rider
[Unforgiven is a pretty awesome Western, as well] -
Any of the Dirty Harry movies
Dirty Harry
Magnum Force
The Enforcer
Sudden Impact
Dead Pool
[Tightrope and The Gauntlet are pretty cool, too, but they’re not Harry.] -
Any Indiana Jones movie
Raiders of the Lost Ark
Temple of Doom
Last Crusade
Crystal Skull (yeah, even that one) -
Almost any Jack Ryan movie
[Sum of all Fears…not so compelling]
Hunt for Red October
Patriot Games
Clear and Present Danger -
Any of the Lone Wolf & Cub movies
Baby Cart to Hades
Sword of Vengeance
Baby Cart at the Rivy Styx
White Heaven in Hell
Baby Cart in the Land of Demons
Babby Cart in Peril -
Lethal Weapon 1 through 4
-
Bruce Lee – Any of his movies or the 1960’s Green Hornet
-
Jackie Chan
Battle Creek Brawl
Rumble in the Bronx
SuperCop -
Jet Li
Fearless
Danny the Dog
Kiss of the Dragon -
Any of the Bourne Trilogy
-
Great movies about education/smarts
Good Will Hunting
Dead Poets Society
Finding Forrester
Stand and Deliver -
Chow, Yun-Fat
The Killer
Hard Boiled
Replacement Killers
The Corruptor
Crouching Tiger/Hidden Dragon
Zorro, the Black Fox (Alain DeLon)
Blade Runner
Princess Bride
Highlander (Directors Cut, please)
Three Musketeers & Four Musketeers (Richard Lester directing)
Cyrano de Bergerac (Jose Ferrer version)
Young Guns I & II
Quigley, Down Under
Tombstone
True Lies
Total Recall
Terminator I & II
Predator
Anchors Aweigh
Big Trouble in Little China
Mr. & Mrs. Smith
Spy Game
Streets of Fire
Serenity (Firefly)
Amistad
Glory
Gandhi
There are several James Bond movies I’d watch any time, but I don’t tend to remember the names until I’m seeing a scene.
Love Jaws, Tremors, Galaxy Quest.
Add “The In-Laws” (serpentine!) and “Blues Brothers”.
Oops, almost forgot “Walk Hard”.
I need to add The 13th Warrior! It was on this weekend and I watched the crap out of it! I could watch it every day.
The Godfather I & II
Groundhog Day
Goodfellas
Ghost World
Airplane!
About A Boy
The Big Lebowski
Miller’s Crossing
Out of the Past
Play Time
Withnail & I
Brazil
Mystery Train
Repo Man
Better Off Dead
Caddyshack