I have whole playlists devoted to just such moods. After a quick scout:
Faces in Disguise - Sunny Day Real Estate (not on youtube.)
Busted, Broken, Forgotten - Art of Fighting (not on youtube.)
Farewell Transmission - Songs: Ohia/Magnolia Electric Co... Jason Molina is one of my favorite singers (not on youtube.)
Aeon - Antony and the Johnsons <-- Can't find the studio version which is sublime but you'll get the idea.
Forget Her - Jeff Buckley
Lover, You Should Have Come Over - Jeff Buckley
No one's Gonna Love You - Band of Horses
The Art Teacher - Rufus Wainwright
The Velvet Cell - Gravenhurst
Hope There's Someone - Antony and the Johnsons
Sand River - Beth Gibbons (Portishead) and Rustin Man
Going Nowhere - Elliott Smith I love Elliott Smith.
Ratts of the Capital - Mogwai
Flame Trees - Sarah Blasko (Cover)
Autumn Leaves - Eva Cassidy
I also love Dead Can Dance, post-rock, ambient/electronica when I'm in that certain mood. Will post more on the weekend if this thread is still going.