Grave of the fireflies for me too. I could never watch that again ever, it is too heart rending.
Pay it forward got me howling.
Totoro, when granny runs to meet mai after she is found, *sob*
Anna and the king (the modern version of The king and I) when various peeps die and/or are killed.
Signs, when his wife dies. Parts of that film are totally hilarious too. I love the foil hats.
The BBC adaptation of North and South by Elizabeth Gaskell. When they meet up by accident at the railway station, blimey.
And lots that peeps have already mentioned.
I kept tearing up throughout The Chronicles of Narnia, The Lion the witch and the Wardrobe but that was purely from yawning my way through the whole boringness of it.