From the link at:
http://www.boxofficemojo.com/alltime/world/
I've seen 95 of them (though plenty of them I wish I hadn't). The ones I haven't seen:
17. The Lion King
35. Meet the Fockers
79. Beauty & the Beast
81. What Women Want
88. Shark Tale
I'd almost add Tarzan to that, but although I've only seen it in pieces at a time I HAVE seen the whole thing.
Of the ones already mentioned in the thread and a few others I'll add:
Kill Bill 1/2 - which I would have seen at least Part I but the friends who rented it couldn't stand it after only seeing about 10 min. so they yanked it.
English Patient - No interest
Raging Bull - Boxing-related movies just bore the hell out of me, possibly because I so strongly despise boxing as a "sport".
Fight Club - No interest.
All but the first Friday 13th. Well, MAYBE seen one of the others (was there one in 3D?)
Halloween H20 - Halloween 3 put an end to that series for me.
NONE of the Nightmare on Elm St.
Hellraiser
Passion of the Christ - would have seen it but wanted to see it on the big screen but couldn't bring myself at the time to see such a downbeat movie.
Oceans 12 - Enjoyed the first (the remake - never seen the original). Bad reviews largely kept me away from the sequel.
The trends I notice by listing movies like this are that I miss a fair amount of the Disney (ish) animation features and the low-grade franchise slasher flicks.
Another useful link would be:
http://www.imdb.com/chart/top
Not including ones already listed above, I have not seen:
5. Schichinin no Samurai
11. Buono, il Brutto, il Cavitto, II
13. One Flew Over the Cuckoo's Nest
15. Rear Window
18. Cidade de Deus
23. C'era una volta il West
25. Le Fabuleo destin d'Amelie Poulain
31. Eternal Sunshine of the Spotless Mind
38. The Pianist
39. Paths of Glory
41. Sen to Chihiro no kamikakushi
43. The Third Man
Well, that's enough of that one. The IMDB list goes much deeper into foreign and classic American films. I don't see many foreign movies since they require SEEKING them to get to see them naturally. And the thing about classic movies is that unless watching movies is your business (film critic, gainfully unemployed) you're only going to see so many of them. Even if you were to go into Film School right out of high school you couldn't possibly see all the foreign films, art films, and classic films that film snobs tend to insist that you MUST see (which obviously is just so much crap).
Just for grins I'll hit one more list, the American Film Institutes heavily debated top 100:
http://www.afi.com/tvevents/100years/movies.aspx
Again, not including ones already listed above:
12. Sunset Boulevard
16. All About Eve
44. The Birth of a Nation
82. Giant
92. A Place in the Sun
96. The Searchers
97. Bringing Up Baby
If I have interest in movies as they are released I almost always DO see them in the theater. If I have a lesser interest I may wait and catch them on cable (or very rarely see them when friends rent them and invite me over). And classic movies are almost entirely what simply happens to drift across my path which is less and less frequent a phenomenon (I've either seen them before or just NOT interested).