I'm kind of surprised to see that these guys haven't been mentioned on the board yet. I just got my grubby mitts on Black Sheep Boy (2005) and the recently leaked copy of their forthcoming album, The Stage Names. Black Sheep Boy got a lot of praise from tubby guys on the Internet whose job it is to give praise to records like these, but I like it for the most part. However, I like the new release even more. BSB sounded like a clash of two completely different styles (maybe how Elliott Smith being backed by the Hold Steadywould sound). The Stage Names seems to find a nice medium between those two.
According to Last.fm, these are 15 similar bands:
The Mountain Goats 100
Neutral Milk Hotel 94
The Decemberists 92
Band of Horses 91
Shearwater 90
Sufjan Stevens 89
M. Ward 89
Wilco 88
Andrew Bird 84
Wolf Parade 82
Iron & Wine 81
My Morning Jacket 79
Yo La Tengo 76
Silver Jews 76
Spoon 75
Incidentally, Jim Eno (Spoon's drummer) did a lot of the production on The Stage Names.
Anyway, I suck at reviewing music, but give them a spin.