Puff does it for me too - My family nickname was Puff, and my Dad told me that it was because I used to sing Puff the Magic Dragon all the time as a little girl. he died 4 years ago,and I just can't listen to it without missing him soooo much and blubbing like mad - the same reason I can't listen to Tubby the Tuba (!), and also find it really hard to read my DD and DS 'No Matter What' ('Love, like starlight, never dies')
Also When A Child is Born by Johnny Mathis - it is a lovely song, but the bit that sends me into uncontrollable sobs is the voiceover in the middle when he says 'A child that will turn tears to laughter, hate to love, everyone to everyone's neighbour, and Misery and Suffering will be words to be forgotten ...forever!
Also, 'Somewhere' from West Side Story, and lastly, Away in a Manger. Such a simple carol, but my Mum used to sing it to me when I was tiny, and it just reminds me of those happy childhood times - I had to sing it in a Carol Service last year, and just had to mime the words -I honestly can't get past the first line without breaking down!
Sob!