DMMapp (Digitized Medieval Manuscripts App) holds records of more than 500 libraries with digital repositories worldwide. Browse by library or geography, and then click through to access the MSS.
Digipal is a resource for the study of medieval handwriting (especially English handwriting of the eleventh century), allowing comparison of script samples.
The International Image Interoperability Framework (IIIF) supports interfaces which enable better digital sharing of images and metadata by libraries worldwide. If you are interested in digitisation practice, follow them on Twitter.
While you can access a comprehensive list of digital repositories through the DMMapp above, here are a few of my favourites:
Digital Bodleian, books and manuscripts from the library's enormous collection.
Parker on the Web is the online library of The Parker Library at Corpus Christi College, Cambridge. Once upon a time it was paywalled, but now it's freely accessible!
The Digital Vatican Library deprived me of an excuse to visit Rome, thanks to its whopping online collection of nearly 21,000 manuscripts.
The Virtual Manuscript Library of Switzerland (e-codices) houses facsimiles from the country's various MS libraries.
A site dedicated to the Staffordshire Hoard include images of the beautiful objects, as well as historical information and a conservation blog.
The British Museum's online collection features some really excellent photography of medieval objects, as well as historical information. The museum have also worked with a number of partners to make parts of their collection available as 3D models on Sketchfab (see my blog post on 3D modelling here).
Select reading suggestions: modern and medieval materialities
Arjun Appadurai, The Social Life of Things: Commodities in Cultural Perspective (Cambridge University Press, 1986).
Peter Baker, Honour, Exchange and Violence in Beowulf (D. S. Brewer, 2013).
Jane Bennett, Vibrant Matter: A Political Ecology of Things (Duke University Press, 2010).
Bettina Bildhauer, Medieval Things: Agency, Materiality, and Narratives of Objects in Medieval German Literature and Beyond (The Ohio State University Press, 2020).
Bill Brown, ‘Thing Theory’, Critical Inquiry (2001) 1–22.
Bruce Holsinger, ‘Of Pigs and Parchment: Medieval Studies and the Coming of the Animal’, PMLA (2009) 616–23.
Catherine Karkov, The Art of Anglo-Saxon England (Boydell Press, 2011).
Leslie Lockett, Anglo-Saxon Psychologies in the Vernacular and Latin Traditions (University of Toronto Press, 2011).
Katherine O’Brien O’Keeffe, Visible Song: Transitional Literacy in Old English Verse, (Cambridge: Cambridge University Press 1990).
Kellie Robertson, 'Medieval Things: Materiality, Historicism, and the Premodern Object', Literature Compass 5 (2008) 1060-80.
Mercedes Salvador-Bello, Isidorean Perceptions of Order: The Exeter Book Riddles and Medieval Latin Enigmata (West Virginia University Press, 2015).
James Paz, Nonhuman Voices in Anglo-Saxon Literature and Material Culture (Manchester University Press, 2018).
Winfried Rudolf, ‘Riddling and Reading: Iconicity and Logogriphs in Exeter Book Riddles 23 and 45’, Anglia 130 (2012) 499–525.
Harriet Soper, 'Reading the Exeter Book Riddles as Life-Writing', The Review of English Studies 68 (2017) 841–65.
Leslie Webster, Anglo-Saxon Art: A New History (British Museum Press, 2012).
I'm also waiting on the edge of my seat for Jacqueline Ann Fay's forthcoming book, Engaging Matter in Early Medieval English Texts (Oxford University Press), 'which examines Englishness in early medieval England as a specifically embodied identity'.