Describes the "National Inventory of Documentary Sources in the United States" (NIDS-US), a microfiche resource of finding aids for manuscript collections and archives. Discusses its companion, NIDS-UK (United Kingdom), the NIDS CD-ROM index, and the development of ArchivesUSA, a CD-ROM which will combine NIDS, the National Union Catalog of Manuscript Collections (NUCMC), and holdings information of archives and repositories. (PEN)