ColLib is a mix of open access harvesting, tagging, and a wiki. It collects information about papers that are freely available on the web, and lets you assign tags to say what they’re about. Then it groups together everything with the same tags.
colLib harvests metadata-records from OAI-PMH-compliant repositories and enables manual ‘tagging’ of these records to cluster them by subject or other meaningful categories. Tags are represented by pages in a wiki, that can be annotated with links to related tags, external links and any other text deemed relevant.
I mention this because it has four articles listed under FRBR. They may be new to you; if not, it could be worth watching the page to see how it grows, or to help it grow.