SuperCal is a visual display calibrator capable of measuring and correcting most conventional displays, including LCDs, CRTs, and projectors. SuperCal doesn't require any hardware measurement devices - only your eyeballs - yet it can be much more accurate, based on how well you pay attention to what you're doing :).
Nearly all existing calibrators assume that you have a display that behaves like the textbook ideal CRT. They don't consider the fact that LCDs don't behave like CRTs at all, nor the fact that most displays have flaws. This is where SuperCal comes in. SuperCal lets you accurately measure the response of any display and build a profile with a corrected gamma table that improves the appearance of your display. When your display is properly calibrated, you'll notice much smoother tonal gradations and cleaner-looking anti-aliased text.
SuperCal was designed to provide the most accurate calibration possible without the use of a hardware measurement device. Very few users can afford to purchase a hardware calibration device, but all users need a properly calibrated display, whether they are retouching digital images or shopping for clothing on the internet.
Note: Now requires OS X 10.7 or later