the adsense account that you have created. nothing else. but after that you can't use the same site, same mail, same IP to create another account. so be careful.
Be careful, Google has a lot of influence. If you're into spammy tactics, sooner or later your AdSense account will be banned, thus rendering all your ads useless and the money that hasn't been paid out to you will be returned to the advertisers.
Why do anything to risk it? Then the possibility of Google banning your domain/ url from their search engine. Not worth it IMO..
Google will ban you for reasons beyond your control including hostile clickers. Stay squeaky clean and you'll still be banned. How many advertisers have been refunded? Approximately ZERO...