Tool's "10,000 Days (Wings pt.2)" gets me every time.
It is about Maynard's mother, but it could just as easily have been about my mother. There are a ton of similarities between his mother's story and my mother's story. In fact, if the lyrics "Judith Marie, unconditional one" were changed to "Helen Mary, unconditional one", it would totally fit my mother. My mother died shortly after that album was released. I love that album, and I listen to it a lot, but I don't think there has been a single time I've heard that song that I don't turn into a blubbering pile of jelly for at least a few minutes.