A crumpled dollar bill floats above a magician's hand.
Because it is so simple to perform, this parlor trick is one of the first many beginning magicians use.
All the magician needs is a dollar bill (it may be borrowed) and a drinking straw (if it's borrowed, it should not have been previously unused). While crumpling the bill into a loose ball, the magician chews on one end of the straw, as if it is a nervous habit. The spectators will take no notice of the straw, since the crumpling of the bill is so inherently fascinating.
The magician holds one hand out flat and places the crumpled ball into it. By breathing out hard through the straw, the magician can direct a carefully aimed stream of high-speed air at the point where bill meets palm. The air bouncing off the palm will lift the bill, making it appear to float in the air.
After some practice, the magician can turn to using an inch-long piece of straw hidden in the mouth and brought to the lips at just the right time through judicial use of the tongue, keeping it invisible from the spectator's perspective and adding further mystery to the effect. A magician may also get the bill to float for an extended period of time by taking a very, very, very deep breath before executing the effect and continuing to breath out until the lungs are empty. (Note, however, that this particular method can cause light headedness, fainting, dizziness, unconsciousness, and -- on blessedly rare occasions -- death.)
Note: Those with particularly strong lungs may be able to make larger denomination bills float -- fives, tens, even fifties or hundreds with the help of a personal trainer.