The US Food and Drug Administration keeps an eye on online sales of drugs.
It has recently targeted 136 websites that appeared to be engaged in the illegal sale of unapproved or misbranded drugs to consumers in the USA.
Interestingly, in addition of sending letters (letters, really? No e-mails?) to the operators of these websites, they also notified ISPs and registrars that a violation of U.S. laws occurred. According to the press release, they expect the registrars to "suspend the use of domain names".