I like The Arduino a lot so I decided to make a Instructable for a L.E.D. MOOD-LIGHT that goes like this:
Green=on
Yellow=on
red=on
Green=off
Yellow=off
Red=off
And So on.

Video 24.wmv
Download

Step 1: -=Parts=-

You Will Need:
1x Yellow LED
1x Red Led
1x Green Led
?x Jumper Wires
3x Resistors
1x Arduino UNO
1x Solder-less Breadboard
20x Minutes

Step 2: -=Place the LEDS=-

Put The LEDS onto your breadboard as show in the picture.

Step 3: -=Connect the Negative Leads=-

Connect the negative leads of the LEDs to the negatve rail.

Step 4: -=Add the Resistors=-

Add the resistors to the positive leads on the LEDs.

Step 5: -=Connect GND to Negative Rail=-

Connect the GND pin on the Arduino to the negative rail on the Arduino.

Step 6: -=Connect Pin 13=-

Connect pin 13 on the Arduino to one end of the resistor connected to the green Led.

Step 7: -=Connect Pin 12=-

Connect pin 12 on the Arduino to the resistor connected to the yellow Led.

Step 8: -=Connect Pin 8=-

Connect pin 8 on the Arduino to the resistor connected to the red Led.

Step 9: -=Get Coding=-

This is the Code:
(Made By Me)

Just copy and paste into ARDUINO!

/*
This Code Is Made By Building_Boy For Instructables.
It Will Cylcle Through A Red, Green, And Yellow L.E.D.
*/

void setup() {
//Delcare pinModes
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(8, OUTPUT);

}

void loop() {
digitalWrite(13, HIGH);   //Turn On Green LED
delay(250);              //Delay
digitalWrite(12, HIGH);   //Turn On Yellow LED
delay(250);              //Delay
digitalWrite(8,HIGH);     //Turn On Red LED
delay(250);              //Delay
digitalWrite(13,LOW);     //Turn Off Green LED
delay(250);              //Delay
digitalWrite(12,LOW);     //Turn Off Yellow LED
delay(250);              //Delay
digitalWrite(8,LOW);      //Turn Off Red LED
delay(250);              //Delay
}