One of the most simple tricks involves only two things - your hand and a coin. You can do this trick anywhere - impress a date, wow a barmate!
Take a large coin in your right hand - a quarter or half dollar works well. Hold the coin between your thumb and forefinger. Put your left hand palm-up on the table with the fingers curled up. Move your right hand low over your left palm and act as if you're dropping the coin - but really just tilt your right hand so the back of your hand faces your audience, while you curl closed your left hand into a fist.
Stare at your left hand as you do this, so everybody looks there too, thinking the coin is now in your left fist. Move your right hand back to your side where you can drop the coin in your pocket.
Now count 1 ... 2 ... 3 ... and open your left fist! Voila, no coin!