This is my entry to the Sparkfun Microcontroller contest so if you think it's good, please vote!!(voting starts the 14th feb). Thanks!!
Once everything is set-up, you will be able to control the color of the RBG's from your computer, using the Processing program, and also see the output color in the program( it ain't perfect but it's handy if you want this for remote lighting)
Below is a screenshot of the Processing executing. By clicking (and/or holding) on the up and down arrows, you can change the color levels of each of the colors in the RGB.
Step 1: Equipment
http://arduino.cc/en/Main/Softwar e and http://processing.org/download/
An Arduino(make sure it has PWM outputs, which is all/most)
USB cable(for the Arduino)
If you are using more than one RGB, you may need to calculate the different values for the resistors. Follow this tutorial http://www.sparkfun.com/tutorials/219 or use this site http://led.linear1.org/led.wiz to calculate the required resistances.