I really like Panic! at the Disco, Fun., Florence + the Machine, and The Killers. They're not super underground indie, but I'm pretty sure they're considered indie genre wise (at least my iTunes says so).
My favorite indie bands are, Etienne Sin (Solo Artist), Insane Clown Posse (Alot of people don't know that they're indipendent) and Tech N9NE (Best selling indie rapper)! and that's just to name a few! ^_^