The annual Farm Aid concert will take place at the Tweeter Center in Camden, N.J., near Philadelphia, on Saturday (Sept. 30). Willie Nelson, John Mellencamp, Neil Young and Dave Matthews will return as headliners to raise money and awareness for the organization. Additional guests include Jerry Lee Lewis, Steve Earle, Allison Moorer, Shelby Lynne, Nitty Gritty Dirt Band, Los Lonely Boys, Arlo Guthrie & Family, Gov't Mule, Steel Pulse, Jimmy Sturr & His Orchestra, Pauline Reese and Danielle Evin. The mission of Farm Aid is to keep family farmers producing food on their