I Will Follow You Into the Dark - Death Cab For Cutie
I have undying love for this band. This song, especially, has been stuck in my head lately. I was actually this close to using it as the song I walked down the aisle to, but a bunch of last minute changes were made and it just didn't happen. It's still one of "our" songs though. Yes, I know it's kind of a morbid song, but I adore it and it makes me tear up every time.