I can devise a method of using Serv.Var("REMOTE_ADDR" and then crosschecking it with a field that contains a list of IP addresses in order to ban someone, however, many people have dynamic IP addresses, so this would be ineffective.

Is there any way of detecting if the user has a static or dynamic IP? Is there a better way of Banning? I was thinking, that cookies wouldn't work because people can just remove their cookies. The only unique number that is presented to us would be the visitor's MAC address (but is there a way to detect it?)

To my knowledge, the MAC address is a UNIQUE number on each and every Modem/NIC that is unique in the world. This would be an excellent way to ban. (Of course, they could get off banning by buying a new modem/nic, but that's fine with me)

How to most professional companys ban users?