Rapper Tupac Shakur died over 15 years ago in a drive-by shooting, but that didn't prevent him from performing at the Coachella music festival in California as a hologram. The virtual Tupac was put together by video technology firm AV Concepts with the help of James Cameron's visual effects company, Digital Domain. The hologram effect was created using a system developed by London-based Musion, which uses an advanced version of a 19th century magic trick called Pepper's ghost to make virtual images appear live on stage.
More information on this technology in the recent NewScientist issue:
Via Dr. Stefan Gruenwald