The favorite C. S. Lewis websites of Louis Markos, author of The Life and Writings of C. S. Lewis, Lewis Agonistes, and, most recently, From Achilles to Christ: Why Christians Should Read the Pagan Classics (InterVarsity Press).
The foundation exists to promote the works of C. S. Lewis to the larger public and in the halls of academia. In addition to offering information on the many conferences sponsored by the foundation, this website provides a full list of books by and about Lewis, along with links to all the major Lewis websites.
Perhaps the best one-stop educational site for information on C. S. Lewis. It not only includes an annotated bibliography but also pictures, audio files, forums, and the full text of several dozen scholarly papers.
C. S. Lewis Society of California
There are many C. S. Lewis societies out there, most of which have good websites. This one offers the fullest and most varied resources, including links to interviews and audio/video resources.
The best research museum of C. S. Lewis is housed not in England but at Wheaton College, Illinois. The center also features the books and papers of six writers who profoundly influenced Lewis: Owen Barfield, G. K. Chesterton, George MacDonald, Dorothy L. Sayers, J. R. R. Tolkien, and Charles Williams.
With the film versions of Prince Caspian and The Voyage of the Dawn Treader due out in May 2008 and May 2010, respectively, this is the single best news source on present and future Narnia movies.