This was kind of inspired by the 'which songs have made you cry thread'. What songs can always put you in a good mood? Like no matter what'd going on when you hear the song, you just feel kind of better about everything?
For me, "Keep Fishin'" by Weezer, "Change" by Blind Melon, and "American Girl" by Tom Petty always do it for me. I don't really know why, they just sort of strike up something in me where i feel great while listening to it.