I found this video on YouTube of Darwin Ortiz (magician & gambling expert) showing how easy it is to stack a deck. This is pretty impressive, but I wouldn't recommend trying it out though, it would be a good way to get yourself beaten quite badly!!
He's got several videos on the subject of cheating in live games...best to educate yourselves if you play private live games!
Haha, Learning how to do that makes poker a lot easier ;) But you gotta make sure you're bigger and stronger then all the other people you're playing against incase they catch on ;) LOL!
It's all in how he shuffles them. If you watch the close-up of him shuffling you'll notice how the cards are stacked. He's just able to count quickly + he's got a marked point.