I haven't got a particularly sharp eye for detecting visual defects or color imbalances on my monitor or screen.
However, if you have and you're a design professional or simply have problems with your display, SuperCal is designed as a visual display calibrator that's capable of measuring and correcting most conventional displays, including LCDs, CRTs and projectors. It does require a keen eye for detail, which if you don't have you might find it a bit frustrating. The developers claim that when your display is properly calibrated, you'll notice much smoother tonal gradations and cleaner-looking anti-aliased text.
SuperCal takes you through a series of steps to calibrate your screen. During this process, some of the changes, and color adjustments are a bit concerning but you just have to trust that it's doing the right thing. A handy wizard takes you through everything but since this is an Alpha release, there do seem to be some instability issues. Don't be surprised if SuperCal suddenly closes on you without warning.
If you're disappointed with the built-in calibration tool in OS X or have a keen eye for display details, you'll find SuperCal a super tool.