One of 20th century folklore's most famous examples of selling the soul is the story of Robert Johnson. His guitar playing and song styling is a cornerstone of not only the blues but also rock & roll. He has influenced Muddy Waters, Bob Dylan, Eric Clapton, Keith Richards and Led Zeppelin.
Robert was a fair guitarist as a young man. Then he dropped out of site. When he came back into view, he played like a man possessed. There could only be one explanation: He had gone to the crossroads and sold his soul to the devil in exchange for the ability to play otherworldly guitar. (This took place in the 1930s, when the depression was in full swing and you took work where you could find it.)
"My Soul 4 a Ham Sandwich" features my attempt at Robert Johnson chops, which I acquired through devilish hours of practice.