This articles describes how you can use I2C (TWI) communication, Arduino and temperature sensors to measure 3 different temperatures. It can be very helpful when you want to measure the outside, ...

He hooked up a microphone and a photodiode to the Arduino, allowing him to use both sound and light to trigger his camera, depending on which mode he selects.

The MozziByte Mozzi Arduino Sonification Sound Synth board measures just 45 x 40 x 10 mm when mounted to the Arduino Pro mini.