Sorry for the incredibly late responses guys, I've not been doing too great lately. And I will check those songs out! If you have more, I'd love to know.

Gary jules mad world.its slow and sad and i just love that song

"Call Me Maybe" by Carly Rae Jepsen! Just kidding. ^_^ But that ending certainly did surprise me!

"The Unquiet Grave" By Solas, the saddest English folk song I have head of about longing for a love one.
"By the Glow Of the Kerosene Lights" By The Once, the most depressing song that I cried through, its a song about losing a love one, its done almost with no instrument, and you can hear the emotion from the song.
"The Vole Of Kilbride" By The Once, Its a song about a dying Canadian solider on nomad's land in WWI and his last thought about his girl and friends. The heart and emotions in the words makes cry when I think of the lost souls that took up arms at a time of need.