American Football, DARTZ!, Empire! Empire, Enemies, Fish Tank, Maybeshewill, Minus the Bear, Pele, Piglet, Renaissance Sound, The Speed of Sound in Seawater, Tangled Hair, Thieves of the American Dream, This Town Needs Guns, 3nd, 14 foot 1, 65 Days Of Static.
Dorena, We All Inherit the Moon, Explosions in the Sky, Mogwai, Oak, (The) Slowest Runner (In All The World), God is An Astronaut.
I tried to choose a few and I ended up with too many, it's too hard to choose between them! The first lot are quite up-beat and most are described as math rock, I believe. The second lot are more ambient and instrumental, great for when you're working.
All (or most) of them fall under the post rock genre, which if you can't tell, I love!