I posted earlier about using the TCS34725 RGB Color Sensor board from Adafuit on my Raspberry Pi blog. The TSC34725 connects via I2C, so it is easy t connect to the pcDuino. The same sample Python code that runs on Raspberry Pi also runs on the pcDuino with one small modification.

For more details, please refer to http://bradsmc.blogspot.com/2013/05/tcs34725-rgb-color-sensor-pcduino.html