X-rite has a really neat online Farnsworth-Munsell 100 hue test that you can use to test your color vision. I want to be completely clear that I make no guarantees about the accuracy of this test though. I performed it on a new LED backlit LCD which has particularly vivid colors and scored a 107 on it which is considerably better than my performance using the real thing in a proper viewing booth with a calibrated light source (I got an average of 163 under those conditions). There are a number of reasons the scores could be different as in my case, the least of which is a screen with extra saturated colors. Still, if you want to see what taking the Farnsworth-Munsell 100 hue test is like, this is as close as you're probably going to get on your computer.