Forrest Gump, during Tom Hanks' emotional speech at Jenny's grave. I've seen the movie hundreds of times, yet to this day I still tear up.
Other films that have made me cry to varying degrees
-Big Fish
-Passion of the Christ (I teared up towards the end)
-Imitation of Life (teared up during the funeral scene)
-LOTR: Return of the King (the scene where Sam carries Frodo up Mount Doom)