Which information will you use to differ the unregistered people? You know IPs are not reliable because the most are dynamic...

there are also no option for such things, you would need to change the forum software with patches, if possible...

I think its much easier if you register, you have avatars... hey I will sponsor an animated sig... , you can send Pms and mails to other forum users, you can use the report post option... you can set user on your ignore list etc.

Morgwen