The DMMapp (Digitized Medieval Manuscripts App) is a website that links to more than 300 libraries in the world. Each one of these contains medieval manuscripts that can be browsed for free. The DMMapp is a product of Sexy Codicology, an independent project focused on medieval illuminated manuscripts and social media. It maintains a great blog about medieval manuscripts, especially those that are available online.
The Royal Spanish Library has put online today an interactive version of Leonardo da Vinci's Madrid Codices I & II. There are transcriptions of the text (in Spanish and Italian, click "T" on the bottom menu), animations of many of the mechanical contraptions (click play button "ver animacion") and the "Indice" in the bottom menu organizes the folios by theme.
Ever since something was invented to replace it, people have been predicting the end of the book: The Death Of The Book Through The Ages [more inside]