I have red flourescent lights which are visible through the vents on the side of my Enlight 7237. I have some blue flourescent lights which are visible through the drilled out vents in the front bezel. I also replaced one of the red LED's in my baybus with a blue one and replaced the stock Enlight LED's with blue ones.
I have a pic of the end result
here. As you can see, the red lights really overwhelm the blue ones. Still, it's a fairly sharp combination. However, if I were to do it over I'd go with all red flourescent lights and leave the LED's in the baybus alone.
However, substituting blue LED's for the HDD and Power lights does work well. I think it's because they are recessed and as a result look more ... well ...
blue.