Sim Daltonism works as a floating palette which converts an area under your mouse cursor to the selected type of color blindness — it works similar to the Apple Digital Color Meter sampling utility. There are 8 different types of color blindness to test. Color Oracle works as a menubar item which converts the entire monitor to the selected mode of color blindness, but only offers the three most common forms.
Not only is this just kind of cool in general, but also a great reminder that not everyone sees the world as you do. Definitely something to be thinking about when designing for print or web, and I suppose all visual art in general.
Things like this always remind me of the limited nature of perception in general, and not just the narrow band of the electromagnetic spectrum we humans are able to perceive, but also that potential blind-spot-of-all-blind-spots called the mind. Sometimes a narrow approach to thinking or creating is no different than being color blind — you’re seeing what’s there, but not the full spectrum.