May 8, 2011, marks the 100th birthday of Mississippi Delta bluesman Robert Johnson, who, according to legend, sold his soul down at the crossroads of Highway 61 and Highway 49 in a midnight bargain that has haunted the music world for three-quarters of a century. The ‘deal’ brought forth Johnson’s incandescent guitar technique and a run of 10-inch 78 rpm singles for the Vocalion, Oriole, Conqueror and Perfect labels recorded in San Antonio in 1936 and Dallas in 1937.