The pilot of the retractable landing gear airplane reported that, the tower controller had cleared him to land behind another aircraft, and that he was distracted searching for the aircraft ahead and did not extend the landing gear. He eventually visually located the traffic and continued the approach. He did not hear the landing gear warning horn. During the landing, a passenger yelled that the landing gear was still up and the tower controller called for a go around. He pulled back on the yoke and added power. The airplane aerodynamically stalled, the left wing dropped, impacted the ground, and the airplane came to rest in the grass to the left of the runway. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.