The hologram performance by deceased rapper Tupac Shakur at Coachella has sparked a massive surge of the iconic performer's album sales, as his 1998 compilation "Greatest Hits" returned to the chart after a 12 year absence.  Shakur's "Greatest Hits" set moved 4,000 copies in the first few days, after he appeared posthumously with Dr. Dre and Snoop Dogg, an increase of 571 percent over the previous week's sales.