Up. Oh gods, Up.
I tear up pretty easily. I recall the first time I saw Forrest Gump, at the theater. When Forrest visits Jenny’s grave, talks to her headstone, and gives her the note from little Forrest, I just lost it. Tears streaming down my face. I was by myself and a bit self-conscious so I just let them flow without wiping my cheeks or anything.
Also, Comrades, Almost a Love Story. A very good film out of Hong Kong that won all sorts of awards. Gets me every time, and I’ve watched it a lot.
There are many more I’m sure.
Brother Orchid: Edward G Robinson give the old charwoman a wad of cash and heads back to the monastery.
Irkru: the dying civil servant is found by the policeman at the playground.
Make Way for Tomorrow “It’s been very nice knowing you, Miss Breckenridge”
One example to illustrate how they do this: it takes more than dropping sad or sweet into the script: This Happy Breed: The daughter comes in the front door with the news that the son and his wife have been killed. The parents are back in the garden. *Instead of going back with her and filming this terrible moment, director David Lean’s camera stops in the living room and stays on the door she went through. *By now in the movie, we’ve been present at this family’s private moments and are emotionally invested in them, so keeping us away emphasizes the helplessness of the situation.
Actually, she died in her sleep and “returned” to Titanic. IIRC, the only people you see are people who died during the sinking.
I don’t cry, but I always get a little knot in my throat when Scout turns around at the end of To Kill a Mockingbird and sees Boo.
The Pianist (2001) - when the child is smuggling goods back under the ghetto wall and gets killed
The Wrath of Khan (1982) - when Spock dies, well it did at the time 
not so much on repeats
Kind of silly, but the scene in Batteries Not Included where the punk is trying to get the old woman out of the burning building by going along with her delusion that he is her son; it’s working until she suddenly realizes that her son is long dead and this man is a stranger, she becomes frightened and he has to resort to physically carrying her out against her will to save her life.
It’s weird that the moment this silly, crazy old lady finally becomes lucid is the same moment the violent young punk finds his conscience and does a good deed.
Also, the scene in My Girl where she is at her friend’s funeral and fixates on him not wearing his glasses and has to be dragged away; has me bawling every time.
The way Bride of Frankenstein got me really surprised me when I first saw it. “We belong dead!” is still one of the saddest film moments that I can think of.
I cried during the previews of Warhorse.
Bambie. Each and everytime I see it, I always cry when Bambie’s mom is killed by the hunters.
Beaches. The funeral scene, I tear up everytime.
Penny Serenade. Yep, something always in my eyes.
A few already mentioned here - Gattaca, V For Vendetta, Make Way for Tomorrow (ugh, that last one especially).
and a few others:
I’m Not There
Away from Her
Martyrs (yeah, I’m weird, but there’s one scene that always gets me)
The Boys in the Band
A Prairie Home Companion
Rachel Getting Married (the first time I watched this, I couldn’t talk for a while after it was over)
Across the Universe, oddly enough, mostly during the song Dear Prudence and it gets me every time.
Wit had me weeping so loud I woke up my (then) toddler, I had to go to bed and get up early the next morning to finish it - and wept buckets again. I’ve never been able to watch it since. Damn, my allergies are back!
Well, yes, okay. But the effect is the same. She’s reunited with the people from the ship, including Jack. And I know it’s cheesy and I don’t care. I love it anyway.
As do I - I think that scene truly makes the movie and gives it a “completeness” that was rather unexpected.
For my silliest waterworks:
Home Alone: When the creepy neighbor was reunited with his family.
Oh s–t yes…and in the sequel when Kevin finds his mom at Rockefeller Center…
I have to hide if I’m watching with my kids…
Wasn’t that something? When they did that cute little montage about the couple growing older? I didn’t cry–I had a lump in my throat though, and my wife was bawling her eyes out. Talk about effective.
Think Up was bad? Try watching The Land Before Time without you eyes flooding the whole room. I still don’t know how I watched that as a kid so many times without being utterly traumatized.
Terms of Endearment
Life is Beautiful
The Pianist (especially the scene when Adrien Brody asks for a piece of bread)
Yep. The first 15 minutes of that movie are as perfect as any I’ve ever seen.