How would you keep a shopping mall lively in an era when more and more people are buying their holiday gifts online? The Mall of America has a one-word answer: holograms. It's partnering with mixed reality firm VNTANA on what's billed as the "first-ever" holographic shopping concierge. Visit the mega-mall's Holiday Cottage throughout the season and you can speak to Ellie the elf (no, really, that's her name) for help tracking down top gifts. Ask about how to find an Xbox One for the kids, for instance, and Ellie will point you to the Microsoft Store.