Change the backlight of 2x16 LCD Today I ordered a 2x16 character LCD with white characters on black background. 

Now I am wondering if I can change the backlight LED, which I guess is white for the characters, with a RGB LED to change the character color. 

Did anyone do this before? 
Is it even possible that way? 

I've seen RGB negative LCDs from Adafruit and Sparkfun.
The product you linked looks like a fairly standard LCD module, so it's probably very difficult to swap the backlight LED. Like most electronics, they're not designed to be modified by hand. It would likely need some precision re-soldering.

When you see LCDs with other types/colours of backlight, it's usually because they were originally manufactured that way.