My recommendations (not sure that all of them belong in an indie rock forum) :

UK/Ireland - http://musictodiefor.wordpress...acoustic-showcase-1/

US/Canada - http://musictodiefor.wordpress...acoustic-showcase-2/

I thoroughly recommend Benoit Pioulard, amazing stuff.

Deserve mention:

The Mountain Goats - Not exactly a secret, but if you arent familiar John Darnielle's music it certainly fits the bill. Start with "All Hail West Texas". Before that album its more lo-fi. After that album the production values increase and bass/drums get worked in. There's a lot of good to both eras.

Bonnie "Prince" Billy - "I See a Darkness" is probably his masterpiece. But I like "Lie Down in the Light" almost as much. His newest album didnt grab me as much...

AA Bondy - Folksy, bluesy... Definitely a fit for what you are looking for.

I'd also second Tallest Man on Earth. "Shallow Graves" is one of my favorite albums from last year.