Kyle Banerjee wrote:
>> ...Like it or not, many webmasters who insist on
>> using visual CAPTCHAs (often in combination with JavaScript) are turning
>> away customers. ..
>>     
>
> And not just visually impaired people. I screw these up all the time
> and my vision is fine.
It may also be worth considering that accessibility doesn't just mean 
making a web site accessible to the visually impaired. 

According to the WHO, Globally about 314 million people are visually 
impaired, 45 million of them are blind.

According to the most recent Unesco Institute for Statistics data, there 
are an estimated 774 million illiterate adults in the world.

How many web sites are designed to be accessible the functionally 
illiterate?