MoodLightI used to use this a while back. I would speed it up until I was having trouble noting the change, and try to push the limit. I switched the colors just to alternate between black and white, although for an added reference point, you could change it up, like black-white-green-white-black-etc... I'm sure you've figured it out, but times/second=hZ.
It's a decent tool to see how fast you're noting at, although it's a little bland. I find that noting feels more natural and quick when using a more choiceless style, where you have attention jumping from sights/sounds/smells/tastes/touch/thoughts/feelings freely.