After Led Zeppelin grounded its blimp in 1980, Robert Plant could have taken the easy stairway to continued stardom, but he has continued to take chances that have paid off -- much like Scientology texts, his solo albums have consistently, if quietly, sold quite well. The orgiastic blues screech that Plant perfected for a generation of operatic Metal belters seems to have taken a toll on his voice; as a result, he now sings more and wails less. The Principle of Moments (1983)...  [+]