Sorry to hear that news.

If they are on a dynamic IP you're a little more limited, however, if they have a fixed IP you could simply block it.

Worst case is you have other members on that block of IPs.

You can try reporting the abuse to AOL themselves - though good luck as this method has always met with perfect silence for us in the past.

You can try sending them a stiffly worded email or letter if you know their address. Mention the damages they are causing to you (hint that you will recover those damages from them if they continue).

Frankly IP addresses are useless for identifying and removing sock puppets. Banning IPs doesn't prevent the problem and penalises the blameless, especially if AOL users. There are other services available that use machine profiling and shared databases which are a lot more effective.

The biggest part of users going to internet throw proxy...
But you can do something:
1) handle proxy headers (if any proxy header exist => proxy)
2) detect host name that user come from and compare it's IP with user's IP, if IP's are different => 100% proxy
3) if not 1) and not 2) => it can be real user's IP

[edited by: rogerd at 11:06 pm (utc) on Oct. 28, 2008]
[edit reason] no URLs or specifics, please, per TOS [/edit]

You can also try cookie-focused bans.

One type is a global ignore, which makes the member's posts invisible to everyone else. That's effective as long as he stays logged in to that account.

Another uses a hidden cookie to operate a multi-detection script to alert mods that the same PC is being used by more than one member. If one of those members is banned, it's a good bet that the new user is the same person.

Ultimately, the solution is quick and effective moderation. Even the most persistent abuser tires of the game when a mod can nuke all of his posts in a few seconds, and he has to start all over with a new email, new username, etc.