Analog Gauge provider
You should be able to buy the 0-5V voltmeter from Futurlec, then drive it using PWM from your microcontroller. I think using a voltmeter is more efficient than an ammeter, unless it's a very small range ammeter (otherwise, if it's a 0-100mA ammeter, you'll need to waste 100mA just to move the needle to 100%).

The volt meter I linked to can be opened, and you can replace the scale with your own (or just glue your own on top of it).