Many older songs, actually.. They remind me of my old friends, who moved states away when I was about eight years old. It's strange, I know, but our mothers used to clean apartments together as a second job, and my mom put in a CD while she did, and that's what we always listened to while we messed around and just goofed off. It really only makes me miss them more.
Disenchanted, by My Chemical Romance, and Your Guardian Angel by Red Jumpsuit Appratus also make me sad... Teardrops on my Guitar, by Taylor Swift.. Makes me want to throw something at the wall. ^^