Not so simple....
@Jason: Most firewalls do this automatically anyway, so I would think Yahoo has implemented this already, however it doesn't work with BotNet clients because of the distributed nature of a botnet, and it won't work in this case for exactly the same reason.. In this case, the users are the "bot".
@Tom: I think probably that someone trying to get a stripper undressed might be a little distracted and not really be bothered, if they notice at all. However your idea of involving the entire web page in a captcha technology might be a good basis to start from.. For example, you could dot Catcha letters at random places around the screen, or in a circle of several smaller Captcha screens, with instructions to read clockwise or anticlockwise or something.. You're right, it needs work, but it's certainly sounds like a go.. It would be interesting if between the readers of this article we were able to design an uncrackable Captcha system.. El Reg.. We want some of the profits please, or leave it open source!! Actually, no, we want the profits, forget open source! :-)