Checkerboard effect, with square count, and color options.
squarecount (number of squares)
red (amount of red)
green (amount of green)
blue (amount of blue)
For 'greyscale' set all colors to the same amount.
Not sure what it could be used for, but its here.
Files and capx
Based on work/tutorials at Pixel Shaders by Toby Schachman.