that's a hard one... as they are such a 'querky' band and depends on what you like about them..
http://www.musicplasma.com/ and
www.allmusic.com are always good to see similar bands, but in this case I don't agree with their lists too much....
I consider Modest Mouse and Death Cab For Cutie similar, but that may just be me as I found them all at same time and are from similar geography...