He's not all acoustic, but... I've really grown to love Jack Whites style lately. He just writes really good music, and a lot of it is acoustic. Hotel Yorba, We're Going To Be Friends, Love Interruption and Carolina Drama is a few of the acoustic ones that really sticks out for me, as well as the song Blunderbuss. He has also recorded some great covers like Sitting On Top Of The World and You Know That I Know.
Two acoustic songs, a small fistfight and an interview can be found here:
http://www.youtube.com/watch?v=v7UIUhXo43A