X-rite has an online colour perception test for anyabout the level of their colour acuity. All you have to do is move the colour blocks on each line until they represent a left to right hue order. Once da score indicating your level of colour perception. I would be slightly dubious of the its accuracy due to the various properties and spectrums of each users monitors. However it does give you a good idea of your ability to differentiate colours.
Interestingly enough the challenge states that:
FACT:form of color vision deficiency. Take the online color challenge, based on the official FMX-Rite.
Give it a go!
(via Phil Dunlop)