A lot of my faves have been mentioned already, but of the unmentioned ones are:
Muse (serious musical talent like WOW)
The Killers (plz come back from Hiatus!)
The Airborne Toxic Event
The Red Hot Chili Peppers (probably one of the reasons I went to LA for college)
The White Stripes
There are a bunch of indie bands I love too that no one's ever heard of but I'll leave it at that ^w^