Analog panel meters are not as blingy as LEDs but they add a touch of elegance and are easier to read quickly.
This one is fairly large and is easy to open up the front with two screws and replace the gauge. There's a 'zero adjust' as well. The back has four 3mm (4-40) screws, 6.5cm apart, so its easy to attach to a box or enclosure
Size: 3.125" (8 cm) square, 1.25" thick (the panel is 0.5", the coil sticks out another 0.75")
To use with a digital output microcontroller (such as an Arduino or AVR), connect the black wire to ground, a resistor in series with the red wire and the other side of the resistor to a PWM output. Then sweep the output from 0 to 100% PWM to swing the meter. The resistor should be = (Power supply Voltage) * 20,000. So for a 5V supply, 100Kohm. For a 3.3V supply, 66Kohm.