Designer Jinsun Park from Korea has come out with a simple tool called Color Picker. Place the pen against an object and press the scan button, the color will be detected by the color sensor and the RGB cartridges in the pen will mixed the required inks to create the target color.
(http://i32.tinypic.com/dvn0o3.jpg)
(http://i32.tinypic.com/4kwqqb.jpg)
(http://i29.tinypic.com/x3vloz.jpg)
(http://i27.tinypic.com/2uz4gmw.jpg)