TraverseLegal makes a good point in its The Basic Principles of Media Law: What You Should Know When Starting Or Running a Website or Online Business:
"There is a common misconception that the seeming anonymity and accessibility of the Internet makes it much like the Wild West. Most Internet users do not understand that every published message board or blog post is subject to a myriad of state and federal laws, many of which were in place long before the creation of the Internet. Internet posts can subject a poster to liability for defamation, invasion of privacy, right to publicity infringement, and trademark or copyright infringement. Additionally, a user’s posts can subject an information service provider to vicarious liability for copyright and trademark infringement, or for the republication of defamatory statements."