@1996 - yeah I have that... but if someone clears their cookies it's of no use. :(

I have a mod on mine that detects you already have an account and shows it as registrations disabled

I think that if Java is enabled you can grab these credentials cant you?

Bear in mind if i had to load a java app on every page I'd never visit the site twice.

We had someone who kept re-registering, he was using all kinds of IP's so it was impossible to stop him from continue registering. In CP/vBullitin Options/User Banning Options, you can put the user ID# in the tacky goes to coventry. It basically puts them on everyone's ignore list. So no matter what they do, no one can see it. They think we are still seeing what they say, but we can't. It's worked like a charm. And we don't have to keep banning him.

Is there any way to store a cookie on someone's PC when you ban them, thus banning future registrations while the cookie is present? That would be a good way to prevent those rolling IP's from re-registering.

nope