A lot of people will tell you to try out some of the newer "avant-folk" stuff that's been en vogue recently, like Devendra Banhart, Joanna Newsom, Animal Collective, and the recent Vashti Bunyan reissue, but I think that if you're an Iron and Wine fan, you might more readily take to 90's slowcore acts like Low, Radar Brothers, Red House Painters, or maybe Jason Molina's Songs:Ohia or Will Oldham (aka Bonnie "Prince" Billy).
Of course there's the Nick Drake card to play too.