Submit Form: Validation Form Question

Is there a script anyone could point out to me for creating a 'question required' feature for submitting forms?

Thanks! /mark

To clarify this question a little more - I"m referring to a robot-proof validation for submitting forms. Numerous captcha versions, inlcuding a jQuery version which is awesome, but I never see the question format. It is used on this website - but the script I don't see developed anywhere as a plugin unless I'm missing it..the Web is a big place ;)

Anyone seen one around or have one to share?

/m