Hearing my grandfather call my name when I was alone in my apartment and he had been dead for seven years. Mind you, he died in (and had never been outside of) the States and I was in my apartment in north France. Still gives me the chills.
Edit: Thanks for the suggestions on its origin! The only thing is that I thought I've heard people call my name or say something to me before when they haven't or when no one is around, but this was much different. It was crystal-clear when I heard him, usually if I think I hear something of the sort, it's not as readily distinguishable in what is "being said." I had also finished posting a status for my family sharing pictures of him and my also deceased grandma and how it was about seven years ago. Maybe that had something to do with it, but I still peered into the hallway expecting to see him there. I didn't respond because I didn't want to egg myself on into lunacy.