Hands down, the biggest tear jerker of all time for me is.....
"Haichi - A dog's Tale". It's at the point that I cannot wait it again, especially since my dog looks just like Haichi as a puppy!
Honorable mentions;
Fox and the Hound
Edward Scissorhands
Dumbo
BraveHeart
Titanic
Lone Survivor (the end really got to me)
The Curious Case of Benjamin Button
Not a movie, but the final 20 minutes of the finale of "LOST" I was seriously messed up for days.