Datacolor SpyderCube White Balance Tool
"It's like, how much more black could this be? And the answer is none. None more black."
So said Nigel Tufnel in This is Spinal Tap, but only because didn't have a SpyderCube. The SpyderCube is more a cube than a spider, and is used for tweaking the white balance and exposure of your photos. Sure, you could just let your camera set on auto white balance (I do) or tweak it by hand later in your RAW processing software (I do this, too), but the SpyderCube is way more accurate, and has something called a "Black Trap", which we believe, although not mentioned in the specs, is the only thing in the universe from which a black hole cannot escape.
Accurate color in digital photos means that the camera needs to know what color the light is. The traditional way is to throw a gray or white card into the scene, snap a picture and then later, back at the computer, use this known neutral color to set the white balance for the whole batch. The SpyderCube is the same, but with a few added features.