Anyone can create a website and use any name they want, I think it would be a brave individual or organisation that would try to sue someone for breach of copyright over a name unless there already was the copyright in place. So if someone does create a site attacking you called http://www.yournameisatwat.co.uk/ don't think you have recourse to law. It is known as cybersquatting, taking over someone's name and using that to promote your message and not theirs. In politics it is becoming a well-used tool. In 2005 the Conservatives created http://www.libdempolicy.org/ to counter the Liberal Democrats' decapitation strategy. The same has been launched by Obama with http://www.johnmccainrecord.com/. The site offers "three things every voter should know about John McCain and... Iraq" for example. The simple message on most of the pages is that McCain is Bush by another name and so Obama and Biden are the candidates that offer real change - the ongoing narrative of his campaign pretty much.
So why is this not on his website, well it is, but why go cybersquatting? Well if a floating voter does go and Googles 'John McCain's Record' it comes up as the fourth hit. If Obama can get this to the top of the search results then voters will see his record before seeing that of McCain. I am not sure if McCain has a similar site, I saw this promoted via a premium ad on http://www.americanblogs.com/ at first I thought it was a McCain paid-for link, another way of capturing voters' attention. Such is the way the Internet allows for innovation in campaign strategy.