My current world project is a world artificially kept at a middle age level of technology (no gunpowder). The population as a whole are kept at this level of development by a group of "wizards" who use science and advanced technology (including nanotechnology) to present magical powers to the people.
I'm sure we have all heard the Arthur C. Clarke quote:
Any sufficiently advanced technology is indistinguishable from magic.
So my question: What traditional magic effects could you perform with advanced technology, given our current understanding of science/physics? (i.e. no handwavium pseudo science)
I'm mostly interested in effects produced locally in non prepared environments, (i.e. you can demonstrate levitation via a massive electromagnetic setup or time travel by travelling near the speed of light, but neither would be much help in intimidating some random village)