Announced today is the Directory of Open Access Books or DOAB. From the press release:
DOAB will provide a searchable index to peer-reviewed monographs and edited volumes published under an Open Access business model, with links to the full texts of the publications at the publisher’s website or repository. The beta version of the service will contain publications of a selected number of academic publishers. The beta version will be made public early spring 2012.
The DOAB will be launched by the Open Access Publishing in European Networks (OAPEN) Foundation.
As there is the long-established Directory of Open Access Journals (DOAJ), it makes sense to have something similar for the burgeoning world of OA monographs. It will be interesting to see how this develops.