Here's a terrific Creative Commons, crowdsourced, online project that provides access to digitized medieval manuscripts all over the world through maps!
The Digitized Medieval Manuscripts Map project was developed by Giulio Menna and Marjolein de Vos in July 2013.
"These maps were designed to help scholars and enthusiasts explore and discover digitized medieval manuscripts made available all over the world. There are hundreds of libraries that have digitized their manuscripts, but it is often difficult to find them."
For example, using this map by clicking on one of the red markers, we learn that the University Library in Rostock has 21 digitized manuscripts available. Clicking the link provided by the map takes you right to them!
The State Library in Berlin has 261 and the Rare Book Department at the Free Library in Philadelphia has 1015! You can zoom in on the map to find more specific locations, and fly around the world to see what resources are available in different countries.