I should add I've seen the last three bands at this festival, myself this year. I saw a Rise Against headline show in September, I saw Bush open for Nickelback in May, and I saw Silversun Pickups open for Foo Fighters in June.
Grouplove/Portugal. The Man (8/24)
Linkin Park/30 Seconds To Mars (8/29)
Rise Against (9/11)