The British Library has an interesting new application called Turning the Pages, which allows you to look at old manuscripts like Leonardo's Workbook page by page:

Turning the Pages is the award-winning interactive program that allows museums and libraries to give members of the public access to precious books while keeping the originals safely under glass. Initially developed by and for the British Library, it is now available as a service for institutions and private collectors around the world.

...via elearningpost