The pilot stated that the purpose of the flight was to perform several touch-and-go practice takeoffs and landings and then perform practice maneuvers in the local area. The pilot departed the active runway without incident and continued around the traffic pattern. The airplane touched down on the main landing gear and was slightly to the left of the runway centerline. As the nose wheel touched down, the pilot raised the wing flaps and shortly thereafter, he applied full engine power in an effort to takeoff. The airplane began to veer to the left of the centerline. The airplane departed the runway surface and continued into the adjacent grassy area at which point the pilot retarded throttle while simultaneously applying brakes. The airplane collided with the sign and the nose wheel collapsed. During the accident sequence, the airplane incurred substantial damage to the firewall. There was no report of a preimpact mechanical malfunction or failure with the airplane that would have precluded normal operation.