I'm not the crying type but...
The 1503rd vote for da da~ "Grave of the Fireflies"!
Also want to add "Life is Beautiful", though it didn't make me cry.
After getting through the first 20 minutes of snoring Happyville, the black comedy and moving moments flood in. And you'd ask yourself how you'd cope in the same situation.
Oh, and when Optimus died in Transformers.