For starters, I have compiled a short Subverted Public Domain List of a few works published in the 1920's that should either be in the public domain already or were due to come into the public domain in the next few years but for the subversive effect of the Sonny Bono Copyright Term Extension Act.

     Anyone interested in seeking the copyright status of other works may find How to Determine Whether a Work is in the Public Domain helpful, as well as some of the links contained therein.  An excellent site discussing all the gory detail of when works of different classes of works (depending on year of publication, authorship, and other factors) entered or will enter the public domain is Mary Minow, Expiration of Works into the Public Domain (June 28, 2002). 

Reconstructing the Public Domain, by Robert A. Baron.  Use of polemic and metaphor in the intellectual property wars.  Mr. Baron argues that copyright and the public domain are not polar opposites but are crucially dependent on one another.  Through understanding the images and metaphors used in the advocacy battles, he sees the emergence of a true understanding of creativity.

Perspectives from the Art Historical and Visual Resources Communities on the Unconstitutionality of the CTEA.  Arguments against the CTEA from the College Art Association, art historians, and visual resource professionals.  Includes links to sites showing the importance of the public domain to teaching and research in art history and related disciplines.

     Recent Derivative Works Based on Frances Hodgson Burnett's Classic The Secret Garden (1911).  This is just a sample of the huge outpouring of creative, new derivative works based on this classic children's work.  There are movies, cabaret adaptations, radio shows, made-for-TV versions, musicals, stage productions, audio and video cassettes, and even a cookbook.  Just another example that a work does not get lost in "limbo" upon entering the public domain.  Rather, it becomes a part of the general culture, available to current creative artists in building new and desirable works.

     Visit Openlaw's Fun Copyright Questions page, where many different people have offered examples of how later authors have made use of public domain materials.  It includes many examples from the world of music supplied by Tim Phillips.  One of my favorites comes from Mona Lisa Images for a Modern World, which contains all sorts of information on this most famous of all paintings, including a number of Modalisiana Images.  How many of these often imitative, often satirical, often parodical, and even often vulgar or just plain silly images could have been made if this work were protected by copyright?  (Don't forget Congresswoman Bono's suggestion that the copyright term be "forever minus one day" in order to get around the Constitutional prohibition on perpetual intellectual property rights.  If these views had prevailed from ancient times, not even Homer, let alone the Bible, Dante, Shakespeare, or Twain would be freely available to authors today.)

     On Plagiarism, by Judge Richard Posner, The Atlantic, April 2002, uses Shakespeare and Milton, T.S. Eliot, Thomas Mann, and artists Eduard Manet to show examples of "plagiarism" in the sense of unacknowledged copying that is applauded rather than condemned.  The article has links to various versions of these quoted authors's works.  He points out that West Side Story was just "one of the links in a chain of plagiarisms that began with Ovid's Pyramus and Thisbe," including, of course, Shakespeare.

     See Tim Phillips's Chart showing the Cumulative Authorship of "Hark the Herald Angels Sing".  A classic example of how a public domain work can grow and change.

     See Peter Jaszi's visual representation of the stunted growth of the public domain due to the Sonny Bono Copyright Term Extension Act at Copyright's Commons.

     Robert A. Baron, Making the Public Domain Public (Apr. 28, 2000)(very detailed investigation of public perceptions of the public domain)

     Howard Besser, Recent Changes to Copyright: Attacks Against the Public Interest, extended version of 11 Peace Journal 1 (March 1999)(examining copyright history and showing how the advent of digital technology has created new structural and economic conditions allowing content owners to strengthen their ownership rights at the expense of the "social good") 

     Dan Gillmor, Copyright tempest over `The Wind Done Gone' is outrageous argues that the prohibiting the retelling of "Gone with the Wind" from the point of view of a slave is outrageous in its contempt for artistic freedom and could happen only because Congress has continued to extend the copyright on a work that should have entered the public domain already. 

    Survey by Tim Phillips showing that the cost of public domain songs in songbooks is lower than that for copyright-protected songs.   This wholly unsurprising result is presented to counter the implausible claims of term-extension supporters that the public domain does not reduce the costs to the public.   Hopefully more such research will take place with time, so that this result can be completely documented and the false argument of the protectionists finally laid to rest.   See also the Letter from Randy Luck to Senator Spencer Abraham showing the dramatic drop in the cost of classical sheet music when works enter the public domain.

     The Ballad of Dennis Karjala by Timothy R. Phillips.  Satire in the form of a ballad on the politics of copyright term extension and the value of the public domain.

     Economic models of copyright, CPB Netherlands Bureau of Economic Policy, The Hague (March 2000).   Paper that considers the economics of copyright in the digital age.  It argues that the case for stronger levels of copyright protection and enforcement is not as valid as it appears at first blush.   This paper supplies an excellent review of many studies on the economics of copyright.  The analysis throughout emphasizes the need to consider public welfare in the form of better access to increasing numbers of works, rather than merely alleged disincentives to publish resulting from easier copying technologies.

     The Purpose of Copyright by Lydia Pallas Loren.  An excellent discussion of the basic goals of copyright protection and its fundamental role in promoting the progress of knowledge and learning.

      Should Auld Copyrights Be Forgot?  Ever wonder what happened to It's a Wonderful Life?  That now famous work entered the public domain when the copyright owner failed to renew the copyright.  (Under the old system, renewal in the 28th year was mandatory to maintaining the copyright.  Now that path leading to more value to the public has been closed, by Congress's making renewal automatic in 1992.)  Had we been operating them under our current system, this classic film would still be gathering dust (and literally rotting away) on studio shelves.  This is one of the clearest and most dramatic examples of the value of the public domain.  Sam Williams has done a story on this work, together with explanations of how the assignees of the original copyright owner are trying to reclaim the copyright (by claiming a continuing copyright in the musical score).

      Mickey Mouse -- A Truly Public Character.  Is Mickey Mouse already in the public domain?  ASU law student Lauren Vanpelt argues that he is--because Disney failed to attach the required copyright notice to the early versions in which this venerable mouse appeared.  It would be bittersweet irony if a court ultimately should hold Mickey to be public property.  Disney was one of the strongest lobbyists for the shameful Sonny Bono Copyright Term Extension Act, largely because they did not want the public to enjoy Mickey Mouse in the same way it enjoys Santa Claus.  If Mickey is in the public domain, Disney will have failed to achieve its goal, but the relatively small benefit to the public (getting free use of Mickey) cannot be offset against the huge public loss from the many other works that are now protected for an additional 20 years.

Douglas A. Hedenkamp, Free Mickey Mouse: Copyright Notice, Derivative Works, and the Copyright Act of 1909, 2 Va. Sports & Ent. L.J. 254-279 (2003)(based partially on an  by Lauren Van Pelt's piece above)(concluding that Mickey Mouse is, indeed, in the public domain).

Cecil C. Kuhne III, The steadily shrinking public domain: inefficiencies of existing copyright law in the modern technology age, 50 Loy. L. Rev. 549-563 (2004), argues in favor of a 30-year copyright followed by 10-year renewals, for no more than a total term of 100 years.