In a post from the Library of Congress’s blog The Signal, Mitch Fraas (Scholar in Residence at the Kislak Center for Special Collections, Rare Books, and Manuscripts at the University of Pennsylvania and Acting Director, Penn Digital Humanities Forum) discusses the use of Viewshare for mapping library book markings. In particular, Frass highlights a project at UPenn that seeks to digitize library book markings from books looted by the Third Reich and recovered by Allied Forces to show how “digital tools might help scholars reconstruct historical libraries and networks of texts.”
Also have a look at their vast (and visually stunning) digital collection of rare book provenance markings on Flickr.