Zsolt Bitter developed great project that can be used in disco parties. This is smart discolight effect mashine which converts bass beats in to light pulses.
The lights are not only beating, but also rotating at random directions due to motor rotated mirror set on parabola shaped base. All this beauty is controlled by PIC 16F84A microcontroller which detects beats and after beat is detected it turns the motor for random time at some direction. It also depends on beat tempo. All of this control is only a matter of algorthm. Project might be a little challenging like any other design where mechanical moving mechanics is present.