The Weakerthans - Download the cd "Left and Leaving" - Mellow cd, great!
Sunny Day Real Estate - anything by them is mellow
Dashboard Confessional - you probably listen to this one

Agree with Sunny Day. Try the first four Elliot Smith albums.

Hystaria--Muse
One Chance--Modest Mouse
Beast of Honner--Auf der Maur
Slow Hands--Interpol

Anything by A Perfect Circle, Air, and some songs by Tool.

while not quite emo, DCFC - transatlanticism puts me right to sleep

I hope you like this song because I have really enjoyed it. You can download it off of pure volume. Mashlin-"violet" It is very soothing

geronimo by unwritten law
before i go by unwritten law
asleep in the chapel by thursday
war all the time by thursday
i wont see you tonight pt 2 by avenged sevenfold (relatively mellow but not exactly emo)