This Tip is from Apple Tip of the Week Two Seconds to Sleep
Want the fastest way to put your Mac right into a deep, sleepy-bear hibernation-like sleep (no whirling fan, no dialogs, no sound — nuthin’ — just fast, glorious sleep). Just press Command-Option and then hold the Eject button for about 2 seconds and Zzzzzzzzzzzzzz. It doesn’t get much faster than that.
Image Credit: elPadawan