There aren't many songs with a scientist as the main character, but Coldplay's "The Scientist" is one of their biggest hits. The guy in the song is brilliant, but despondent because he's lost his girl after neglecting her for his work.
"Kickstart My Heart" is about all the ways Motley Crue gets their blood flowing without drugs. It was inspired by their bass player Nikki Sixx, who claimed he had to be revived with a shot of adrenaline to the heart after an overdose.
The song "Sadeness" by Enigma (the one with the chanting monks), got its name from the French novelist Marquis de Sade, who believed sex had to be painful in order to be pleasurable - thus the word "sadism."