Smithsonian.com, the Internet face of the venerable Smithsonian Institute, has published a short feature highlighting works of literature which no longer exist.
Writers such as Jane Austen and Ernest Hemmingway all had unpublished works which never saw the light of day. Others, such as Homer and Shakespeare have had works passed on to legend because of the lack of technology to reproduce the works in quantity.
In another instance an anonymous Franciscan monk from the 14th century wrote a travelogue of his journey to the arctic. Five copies were produced, but the knowledge only survives through a third-hand account of its contents.
View the full list here.