If you mistype a domain name, you might be taken to a site with Google ads. I actually (mis)typed livejournall (while not logged in) and it took me here. (Mouse over or show the sponsored links and note where they're going.)

While this isn't necessarily fraud, I think it's lame to make money like this. There are some people who feel domain parking is in violation of trademark law, however. Also, some advertisers are pulling their ads off of networks that display ads on such sites, because they generally don't convert well and may be click fraud targets.

BTW, I hear that the domain registration business is starting to boom again. Some domains have sold for around US $1 million, sparking a rise in registrations. Things like this give me more reason to think we're in another bubble.