Always look at the bright side. Ripping means that they really want their community to be like yours, something like a wannabe. You could calmly contact your host or send the ripper a notice that you will take action if he/she does not take it down by a certain amount of time.
But if the ripper do know what he or she is doing and pose as your website or endanger your members in some sort, you could get more 'agressive' and just report it to a higher authority that is in charge of the website, the webhost etc.
Please do not e-mail the ripper with warnings that you would take legal action ( unless you're really serious..which not a usual sight ) because most rippers knows that such threats is not serious, and they might even do more damage to the forums or whatsoever ( hacking etc. ).
Ok, that was long.
I usually contact them and issue a cease & desist telling them to remove the skin or face legal action. 9/10 they remove the ripped work and the issue is dealt with but sometimes i've had to contact their host and have had their websites and domains taken down.
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