This is an interesting concept brought to you by the people at Nike. The Nike FeelFree headset sits on top of your head and sends vibrations through your bone, at varying frequencies. Vibrations above 40Hz will increase your perception and help you solve problems.

Waves between 13 and 40 Hz will increase your sense of concentration or induce arousal, and waves between 7-13 Hz can help you relax, or make you feel drowsy. By setting the unit for waves between 4-7Hz, you can help induce REM sleep, and lowering the frequency to below 4Hz is associated with a deep, dreamless sleep.