I'm sure I'm not the first to think of this idea but I came up with this trick as I had a deck in my hands (marked) and someone was asking me to do a trick.

So I had them take a card, look at it, put it back in the deck during a dribble and then I immediately hand them the deck to shuffle. When I get the deck back, I tell them I think I can find their card. I do, after some byplay and indecision, pull it out and cut it to the top as I'm looking at the cards. Then you build up the reveal however you like, but turn over a double so that the card is wrong. Act surprised or shocked that you were wrong, turn over the double, and deal down in front of you saying, well that one's not it, strike one (or something like that). Now I tell them okay think of your card, project it onto a whiteboard in your mind where it is the only image there. Okay, I think I've got it. Now grip the cards down at the short ends. Face the opposite side short ends so that when you pull and riffle the short ends facing the card, it creates a burst of air that moves the card.

Now just turn over the card and watch the crowd react. I'm sure someone has done this before but man this effect is fun as I've had strong reactions so far.

Neat idea! I only just got a marked deck and trying to come up with different routines is super fun.

I have several different marked decks that I like to carry at different times just to run thru at odd moments in order to keep familiar with each marking system. I keep each deck stacked in Si Stebbins order at all times, so if someone suddenly asks me to do a trick, all I have to do is perform a couple of false shuffles with a final deliberate cut (preserving the Stebbins order) and then pretend to "sense" the unseen bottom card of the deck by gently stroking the back of the top card to "read the quantum after-image" left behind by the unseen bottom card that was recently in contact with it. I emphasize that this must be done within a few seconds of cutting the deck, as the quantum image fades quickly. I always get the color of the unseen card right, and usually I can tell paint cards from pips, but I'll often mistake 5's and 6's or 7's and 8's, as they're "hard to count sometimes." --Yeah, I know--I'm completely shameless! But a good time is had by all, and I'll usually confess in the end that there's really some magician's trickery at work.