Hank Williams Jr., Big & Rich, Emmylou Harris, Sugarland and rock superstars U2, Bon Jovi and Elton John are among the latest acts signing on for the ReAct Now: Music & Relief concert special to air Saturday (Sept. 10) at 8 p.m. ET/PT on CMT, MTV and VH1. The special event will raise money for the American Red Cross, the Salvation Army and America's Second Harvest while promoting volunteerism in the aftermath of Hurricane Katrina. Other new additions to the list of talent include Coldplay, Jon Stewart, Pearl Jam, the Red Hot Chili Peppers, Allen Toussaint, Norah Jones, Fiona Apple, Buckwheat Zydeco, Dennis Quaid, George Lopez, Beck, Jewel and Chris Thomas King. The multi-genre special airs air simultaneously and commercial free across MTV Networks' music services and will be streamed live on CMT.com. Previously-announced artists participating include Alan Jackson, Gretchen Wilson, Lynyrd Skynyrd, Kid Rock, the Rolling Stones, Neil Young, Kanye West, Sheryl Crow, Paul McCartney, 3 Doors Down, Kelly Clarkson, Brian Wilson, Melissa Etheridge, the Neville Brothers, Trent Reznor, Motley Crue, Simple Plan, Dashboard Confessional, Goo Goo Dolls, Staind, Good Charlotte, Audioslave, Common, John Mayer, Marc Broussard, Maroon 5, the Radiators, Green Day, Usher, Alicia Keys, John Mellencamp, Dave Matthews Band, Rob Thomas, David Banner and Linkin Park's Chester Bennington.