There are so many that make me cry. I love music and it always makes me feel happy, sad, nostalgic, weepy, energetic, etc., depending on what song it is.
The one that comes to mind today is "Smile" by Nat King Cole. I listened to that song over and over when I was losing my best friend to breast cancer. I would go be with her and put on a brave face but as soon as I could, I would put on "Smile" and sob. I dreamt about her last night and I have listened to that song several times today.