Before "Pumped Up Kicks" became a top-selling single last year, Mark Foster's greatest hit was the music in a TV commercial for Muscle Milk, a protein drink.
But although the singer-songwriter and his band were nominated for two Grammys and performed live during the Feb. 12 awards telecast, he wrote the songs while working at Mophonics, a Los Angeles company that scores TV commercials and, in a unique partnership, encouraged him to develop his outside recording career.