LibriVox - public domain audiobooks

LibriVox is a volunteer-based library of public domain audiobooks.  Most books are available in MP3 and OGG format.  Go to http://librivox.org/ to start searching.

Some authors of interest:
     -  Karl Marx
     -  Oscar Wilde
     -  Emma Goldman
     -  Pierre-Joseph Proudhon
     -  François-Marie Arouet (Voltaire)
     -  Henry David Thoreau
     -  Leo Tolstoy
     -  John Ruskin
     -  Mikhail Bakunin