On their website they have a new colour vision test which is a movie with a coloured square moving around the screen which changes colour. The idea is that during the 90 second clip people who are colour defective cannot see the square in some places for a few seconds (although I could see it all fine despite failing the ishihara).
It's interesting to see that:
The new version of the colour vision test was produced with support from the UK Civil Aviation Authority. The test is not yet in use for medical certification purposes. It should therefore be used only as a guide.
It can be found at the bottom of this link:
http://www.city.ac.uk/avrc/colourtest.html