RASPICOMM - 

RasPiComm is a tiny Input/Output expansion board designed specifically for the Raspberry Pi single-board computer. It provides a variety of serial communications interfaces, a battery backed-up RTC, 5V tolerant digital I/O (The GPIO pins on the Raspberry Pi are limited to 3.3V) and a Thumb joystick. Full specifications at: http://www.amescon.com/raspicomm.aspx

RS-485 serial channel up to 230400 baud, pluggable screw terminal connector (A, B, Gnd)
RS-232 serial channel up to 115200 baud, pluggable screw terminal connector (Rx, Tx, Gnd)
RS-485 & RS-232 pins are fully ESD-protected by TVS diodes
Real Time Clock/Calendar, battery included powers the clock for approximately 10 years
5 x digital Inputs connected to onboard joystick (4 way + push), 5V tolerant, 2mm pitch external connector, not populated
2 x digital Outputs, 5V @ 100mA max each, 5V relays can be connected without additional circuitry, 2mm pitch connector, not populated
SPI serial channel connector, 2mm pitch connector, not populated
2 x I2C serial channel connectors
Power connector, pluggable screw terminal connector (+, -) either powers the Raspberry Pi and RasPiComm (5V @ 1.5A max) or is a power output when powered over USB
Power consumption: 10mA max (outputs off), 210mA max (outputs on and maximum rating drawn)
Size: 35.2 x 56mm