Haha, there's pretty much nothing heartwarming in collection, but I have a couple.
Perfect Day - Lou Reed
Spieluhr - Rammstein (told you I had nothing heartwarming
Today - Smashing Pumpkins (actually about self mutilation but has an extremely upbeat tune)
ToLoveSomebody - Billy Corgan (vocalist of the above band)
Stumbeliene - Smashing Pumpkins (I'm not obsessed with them, they just wrote all the heartwarming stuff in my collection)