16X2 LCD or 20X4 LCD (2004 model) character display with additional features.
6 push buttons: four arranged like a control pad with four as arrow keys and two more on the side.
2 RJ45 ports to pass as many as 16 long and robust connections to sensors or control devices.
Optional buzzer in place of an RJ45 for tones. You can connect any arduino pin to the buzzer.
Optional sensor block to sense most common sensors, such as thermistors for temperature, resistive pressure sensors, light-dependent resistor for light, Hall effect magnetic sensors etc. You can connect any arduino pin to the buzzer.
Two 3mm LEDs as indicators. You are free to choose which arduino pin to drive the LEDs with.
Real time clock with battery backup keeps the time when Arduino is turned off
EEPROM for easy data logging keeps data when Arduino is turned off
GPS connector and breakout for a GPS module
Reset button for Arduino
All Arduino pins are brought out for maximal flexibility.

The I2C bus is not tied to analog pins 4 and 5 but brought next to them, so that the shield can be used with either Uno-compatible boards or Mega-compatible boards by jumpering to the appropriate connection.

Arduino John Liu Phi-2 Shield Pinouts