Fans of the new adventure fantasy "Clash of the Titans" can also look to the Museum of Modern Art, where a lively exhibition is featuring the work of ray Harryhausen. He's the stop-motion wizard whose special effects have enlivened fantastic films since "Mighty Joe Young" in 1949. On view at the museum are models, sketches, and drawings from movies (realized and unrealized) throughout his career. It's an entertaining show, supplemented with screenings of various Harryhausen classics. His work is more personal, and looks much more old-fashioned, than the computerized visual effects of the "2001" and "Star Wars" generation. For a while, a few years ago, it looked like time and Hollywood had passed him by. But his latest epic shows that he's still in there pitching, and the museum exhibition is a timely reminder of the riches he has brought to the movies for more than three decades. He is a genuine artist, after his own unusual fashion.