You may have heard of a few or all of these but given
Iron & Wine (Sam Beam), my favorite is "In The Reins" a collaboration with Calexico and a close second is a solo live recording at Wheaton college (If you or anyone else can't find this let me know and I'll find a way to get you a copy). But really any Iron & Wine is good, earlier stuff is more sparse whereas the last couple of albums his sound has branched out and become a bit more experimental.
Bon Iver (Justin Vernon), is out of a similar vein as Iron & Wine. "For Emma, Forever Ago" was an instant hit with me and it took me awhile but I think his latest "Bon Iver, Bon Iver" may even be better.
Hayden, I've been listening to "In Field & Town" quite a bit ever since I saw them open for Feist.
Nathan Wiley is a local PEI artist who I've been listening to for years now. I'm still a big fan of his first album "Bottom Dollar" but all are good.
Morphine is an interesting blues/jazz influenced rock band that's heavy on sax and bass and Mark Sandman's seductive vocals. Personal favorites are "Cure For Pain", "Yes" and "The Night".
Off the beaten path would be The Tiger Lillies, I can't adequately describe them but here's a blurb from their website that does a decent job "The Tiger Lillies are an extraordinary three piece band with a large cult following in London. They are fronted by singer Martyn Jacques who trained himself as an opera singer with a castrati style voice of heartbreaking beauty, whilst living alone above a strip joint in Soho for seven years. Accompanied by drummer Adrian Huge, whose appearance was described by David Byrne as James Joyce on drums, and double bass player Adrian Stout, Jacques plays accordion and sings savage and passionate songs about prostitutes, drug addicts and losers, his voice soaring and growling like a man possessed."
I don't usually listen to country but Lucinda Williams is an exception, I quite like "West".
If you haven't already you might try Fionna Apple and Joss Stone as well.