I have managed to find a few secret areas but it doesn't seem to do anything for you, unless there is a holy item. Some secret areas just have a spinning red/green thing. Is there any point to visiting those areas?

Other than the satisfaction that you've found them all, secret areas help you find weapons, armor and other bonuses & potentially artifacts to make utilization of the Black Tarot board easier. ;-)

In some levels, finding all the secret areas is a requirement for unlocking a tarot card (forget which levels though). Other than that, finding secrets gives you bragging rights and not much else.

Edit: Guess I should have checked the original post date