While Mark and I are single-handedly keeping this thread alive, I thought I would pass on a technique for doing the final reveal in a "leader card" type presentation. This does away with all sleight of hand and is the most natural handling I've seen.
I worked it out myself about 20-odd years ago and haven't seen it described elsewhere, but I make no claims to originality.
Situaton is this: On your left is the correct pile -- from the bottom up, AS, 13 or so black cards, AH, 13 or so red cards. On your rigth is the wrong pile -- AD, 13 or so blacks, AC, 13 or so reds.
I'm assuming that each pile is kind of a line, with the AS the lowest card, and each card spread enough to show a little bit of the card below it.
Pick up the left pile -- leaving the AS on the table -- squaring it very roughly. Try to leave the cards spread enough that they are somewhat fanned (although this will be in a straight line).
Holding this pile in your left hand, reach under with your right, withdraw the bottom card, turn it face up, and place it on the AS. Repeat with all the blacks until the AD comes out. Turn it face down and continue to show all the reds the same way.
Now pick up the incorrect pile, leaving the AH on the deck. Turn over the entire pile as one, place it on the AH, and spread downward.
All of the cards in the "wrong" pile now look correct. But in hundreds of performances this was never noticed because the turning over of the entire pack uses the same action as the turning over of the individual cards. It also makes sense, having gone through one half the deck card by card, to do all the rest at once.
I've read many ways to do this final reveal, but none that I've read can match this one. It's completely deceptive, entirely natural looking, dead easy with no manipulation, and has a built-in dramatic punch of revealing the last half deck at once.