The Arduino and audio enthusiast team at CoolArduino have published a fascinating method of creating a truly analogue audio volume control with an Arduino (keep reading). Knowing that tungsten wire (found in bulbs) has a resistance that is proportional to temperature - they control the bulb brightness with PWM control from the Arduino, and pass the audio through a voltage divider comprising of the bulbs which then alters the volume.
Sounds crazy but it works, so visit the project page for a complete explanation. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're new to Arduino, the first step is a solid board for your projects - our Freetronics Eleven - the Arduino-Uno compatible with low-profile USB socket, onboard prototyping space and easy to view LEDs: