Public Record Office of Northern Ireland (PRONI) Catalogue Online

The eCatalogue is a fully searchable database containing over one million catalogue entries relating to PRONI’s archives.
The Electronic Catalogue for Northern Ireland (eCATNI) project was a five year project to convert PRONI’s paper catalogues into an electronic 'searchable' database. The eCatalogue went live onsite in the PRONI Search Room in November 2008 and on the internet in January 2009.
See:
http://www.proni.gov.uk/index/search_the_archives/ecatalogue.htm