how to collect more information at registration?

[kevinh]

I have resorted to manually approving new registrations on the two forums I run to prevent comment spam. I have found this very effective, however it's sometimes hard to tell whether someone is a genuine user or not.

I would therefore like to collect some information from new users when they register and their responses will help me determine whether they are genuine or not. This information will be used for this purpose only and will not be shown anywhere else.

Can anyone think of any easy way to do this ?