Note: Gravity: GPIO Shield for Arduino is discontinued now.
An Arduino UNO has a limited number of GPIO pins - but what if it is not enough? The GPIO expansion shield specifically designed for Arduino UNO-type boards. This shield greatly expands the GPIO resources to 36 pins in total, including 14 digital pins, 6 analog pins and 16 I2C pins. In addition digital and analog pins include the DFRobot "Gravity" interface, giving you in-line power and ground pins and saving you having to connect millions of jumper wires for a single sensor.