This was a tough one. There are plenty of songs out there that make me sad, and most of them are schmaltzy crap. Some songs make me sad because I hate them so much (see also DROPS OF JUPITER). However, there's only one song that comes to mind that will make me come close to shedding tears when I hear it. Again, it's by Jimmy Eat World. I didn't want to pick them again because I'm trying to be diverse, but I really had no other choice in the matter. This song helped me through a very tough time (which is partially why it makes me sad), and the story behind the song itself also makes me sad. If you're not familiar with it, do a quick Google search of Mykel & Carli Allen. Good people, tragic story.
Here You Me.