Just stumbled across these handy Mac OS X software applications to help designers and artists simulate the effects of color blindness on-screen: Sim Daltonism and Color Oracle.
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.
