Quite interesting:
http://www.eff.org/issues/bloggers/legal/liability/defamation
http://www.firstamendmentcenter.org/speech/internet/topic.aspx?topic=online_libel
http://www.makeuseof.com/tag/how-to-remove-false-libelous-information-about-yourself-online/
http://suffolkmedialaw.com/2011/02/02/online-rant-leads-to-libel-suit/
BTW, one article talking about get insurance -- sounds like a good idea.