This is Halloween week, when monsters scuttle about. What could be more appropriate than to pen an appreciation of Stephen King, the most successful horror writer in recent history? His books have sold more than 350 million copies. Films based on his work have grossed over $2 billion -- and that's not counting the zanily entertaining "It," released this fall, which by itself has earned over $666 million worldwide. And despite at least two announced retirements and an enforced convalescence following an accident, King, who turned 70 in September, shows no signs of slowing down.