Mark Twain Project Online

The ultimate purpose of the Mark Twain Project is to "produce a digital critical edition, fully annotated, of everything Mark Twain wrote" using innovative online technology. " It offers unfettered, intuitive access to reliable texts, accurate and exhaustive notes, and the most recently discovered letters and documents". MTPO is a collaboration between the Mark Twain Papers and Project of The Bancroft Library, the California Digital Library, and the University of California Press.
Great stuff, fanatastic letters, and a wealth of detail in the notes. Brought to my notice by the Scout Report.

Mark Twain Project:
www.marktwainproject.org/homepage.html