You're missing out on their album
Ágætis Byrjun which is also great. They also have an album released previous to that called
Von, but its not like their other stuff and is a bit of a disappointment to most listeners, me included.
Music like Sigur Ros...hard to find! I think a few instrumental rock acts have a similar vibe about them, bands like Explosions In The Sky, Do Make Say Think, Mogwai, and Godspeed You Black Emperor.
I discovered a band earlier this year called
Adjagas who I gave 5 out of 5 in a review. They're the closest to Sigur Ros that I've heard, they're Norwegian and have an amazing sound. You can check out their
Myspace to hear a few samples.