Can anyone recommend a security question plugin?

I have been looking for hours for a plugin that can allow me to add a tailored security question to my multisite registration form. I just want to be able to add a custom question and answer.

The only one I can find is anti-splog by WPMUpremium, but that has a ton of paid-for options and constantly throws messages into your admin panel.

Can anyone recommend a plugin to me?

Thanks

Jazbo