The Getty Research Institute's Provenance Index Databases allow users to search archival inventories, sales catalogs, dealer stock books, artist payments, and provenance records related to artwork in public collections in the UK and US.
The Provenance Online Project was started by the University of Pennsylvania Rare Book and Manuscript Library to identify bookplates, inscriptions, stamps, bindings, binding waste, and shelfmarks, all through crowd sourcing on Flickr.