David Good calls. Sabbath have many great intros, but Supernaut is possibly the greatest. Whole lotta Rosie for Acdc I reckon. Try also Accept's Fast As A Shark for the birth of Speed metal. And Motorhead's Overkill live for the birth of thrash. Or back to Sabbath that might have been Symptom of the universe, another soul darkeningly good intro. Heavy makes me happy, metal makes me mean.....