múm is great...
Now you'll need to check out Sigur Rós (Ágætis byrjun and the Ba Ba Ti Ki Di Do EP, for example), The Album Leaf (In a Safe Place), Do Make Say Think (and you might as well check out some other Canadian post-rock while you're at it: GY!BE, Fly Pan Am, A Silver Mt. Zion, One Speed Bike, etc.), Four Tet, Mogwai, Explosions in the Sky, Plaid, Board of Canada...
Lots of stuff overlaps with múm