I've just tried the colour blindness tests at the site below, I failed every one. Is it just me? Give it a go.

Colorblind Homepage
(Look for "I want to test my Color Vision", for some reason I can't post links with spaces in them)

Other tests:

FreeHearingTest.com
Test your musical skills in 6 minutes!
The Sheep Reaction Test
Spot The Fake Smile