Illuminated manuscripts are truly a joy to behold. And there are a remarkable number of them available on the web for your viewing pleasure. The most famous illuminated MS is the Très Riches Heures du Duc de Berry. For galleries with multiple images, try the resources at DScriptorium, Web Gallery of Art, and the Leaves of Gold exhibition. Elyse Boucher's page is a work-in-progress detailing the history and methods of illuminating books, with both images and secondary sources; see also Sue Wood's Art and Books page.
Should we think goat when it comes to saving important data? As part of a modernisation campaign the UK Parliament may ditch vellum for computerised records. But what will last the longest?