You only think that what you are posting will remain anonymous on the world wide web.  A federal prosecutor in New Orleans learned that painful lesson recently.  First Assistant U.S. Attorney Jan Mann had been posting anonymous comments on a New Orleans Time Picayune website under the online alias of "eweman."  Her comments were directed at a landfill operator, whose business is the subject of a federal investigation.  The comments apparently criticized the landfill.  The operator filed a defamation lawsuit against Ms. Mann.  

The lawsuit cited several clues leading them to Ms. Mann.  Among the clues were "superfluous" spacing before punctuation marks, and the use of obscure terms such as "fender lizard" which she had used in conversations.  And, her posts attacked persons for whom she was known to have strong antipathy.  She based her alias on the initials of Edwin W. Edwards, former Louisiana governor.  Ms. Mann has been demoted from her former position of First Assistant.  See ABA Bar Journal report

No, "anonymous" is not always what we think it is.