I've been brutal to Andrew Mayne in the past, but as I've said before when he's made something good, it's really good. "Ghost Vision" is that "really good" effect. You borrow someone's cellphone and ask them to put it in video mode. With them watching with you, suddenly they see a ghostly form move across the screen. The beauty is that they have recorded it so they can show it to friends and others to prove what a supernatural time they had with you.
As you expect, this is an effect that will require a good deal of showmanship on your part. If you just say, "Hey, watch this!" it's going to be useless to you. If you incorporate it into a mysterious evening or spooky environment, you're going to do some serious damage to the spectator's sense of reality. This effect is easy to perform and it leaves the spectator with a lasting souvenir of the performance. It uses something perfectly normal--the spectator's cell phone--and gives them a moment of the surreal. There is only about 2 seconds of set-up you have to do, and it can be done while you're talking about the ghostly experiences you've had or heard of or whatever.
The effect also comes with ways to make a chosen card show up, and just a ghostly face if you want to go that direction. Whichever way you choose, this is definitely something that will set you apart from any other magicians your spectators may have seen before.