The TEMT6000 is an ambient light sensor. The breakout board from SparkFun is $5 and is easy to use. Just connect GND and VCC (5V). The S goes to the analog input of your choice and you can start measuring - the greater the incoming light, the higher the analog voltage. Here is the complete TEMT6000 Datasheet .
All the code be downloaded from here.
void setup() { Serial.begin(9600); // sets the serial port to 9600 } void loop() { Serial.printLn(analogRead(0), DEC); // prints the value OF analog input pin 0 delay(1000); // wait 1s for next reading }