Charles Darwin's complete works online

The University of Cambridge has created, The Complete Works of Charles Darwin, a digital library of Darwin's writings. This digital library includes over 50,000 pages of text and 40,000 images of manuscripts and published articles. All content on the site is keyword searchable. Make sure to check out the Audio Darwin section, where you can download MP3s recordings of many of Darwin's writings (listen to the last sentence from the Origin of Species).