The Pi trumps many other dev boards in the same price in terms of processing power but it does lack one key feature: an ADC for analog input. Adafruit just posted a nice tutorial on using an external ADC via SPI to act as volume control for mp3 playback:
I do have a MCP3002MCP3002 which is smaller version of the demonstrated MCP3008MCP3008, so I'm eager to try out some analog action soon.
Cheers,
Drew
