[Meltdown]

Just use a a challenge/response question.

What is the hottest season? What is the coldest season? Capital city of the UK? What are the last three letters of the capital city of the UK?

.. and so on.

Better still to select a question specific to your usergroup.

Regards Melt

[webstartupper]

I guess you mean something like http://textcaptcha.com/ - any feedback on this service?