The pilot was practicing touch-and-go takeoffs and landings in a crosswind. The pilot said the landing was uneventful; however, as the airplane accelerated for takeoff it veered to the left. Despite the pilot's control inputs, the airplane continued to veer to the left, exited the runway surface, and struck a runway sign. The airplane sustained substantial damage to the fuselage, firewall, and empennage. The pilot reported no mechanical anomalies that would have precluded normal operation.