Can anyone name some devices or places where you have seen LEDs [or lights] flash to music or any audio frequency. Also I am not sure if night clubs have these lights that flash to the music but if you know about a club that has this please give me a name. Thanks -_-
Google color organ. What you are talking about is called a color organ so that should get you going. Read this link for several circuits. Most can be easily modified to drive LEDs rather than incandescent bulbs. It doesn't get any simpler.