I have been hit for the past 2 weekends...
Pumps up the bandwidth from about 10Mbps to 25Mbps... when I find them I just delete the user from the password list and redirect them to a page that tells them to fuck off.
I would agree with the chargeback thing that is why I don't even bother redirecting to the main page. I would rather not have the few sign ups that will bring.