I love Sigur Ros, but have become very bored with them lately. I guess listening to them for 5 1/2 years straight could do that to a person.
I also like: The Clash Green Day (old) The Beatles The Rolling Stones David Bowie Queen Weezer (old) Smashing Pumpkins Nick Drake Simon & Garfunkel Nirvana Stereolab Vince Guaraldi lots of others but can't think right now