Relay board for Arduino

So in order to make the Arduino* control things in the car, such as lights, I need to use relays.  So I've made a board that hooks up to 32 of the mega's pins and will give a ground connection for the relays.

As you can see, the wires are all soldered to the relay board, and on the other side is a 32 pin male header plug that fits directly into the mega's female headers.  This allows me to disconnect if I ever need to do work with ease.
The row of screw terminals is where the relays connect.  The relay harnesses all connect to each other, and will be mounted somewhere under the hood, and the ground wires will be routed to this board.

The schematic for this is as follows

The protection diode I used is a 1N4007, the transistor is a 2N3904, and the input resistor value is 2.2K Ohm


*actually I'm using the Seeeduino Mega from seeedstudio