The pilot reported that he landed on runway 33 uneventfully. During the landing rollout he applied the brakes and the airplane veered off of the right side of the runway into mud and dirt. He added full engine power in an attempt to get out of the mud and climb a small incline. He said that the airplane exited the mud, skidded across the ramp, and collided with a parked airplane and hangar before colliding with an embankment. During the accident sequence, the airplane's main landing gear collapsed, resulting in substantial damage to the lower fuselage and right wing. The recorded wind at an airport, located approximately 7 miles west of the accident site, was from 160 degrees at 3 knots. Examination of the wreckage by a Federal Aviation Administration inspector did not reveal any preimpact mechanical malfunctions. The pilot did not report any preaccident mechanical malfunctions or failures that would have precluded normal operation.