The importance of a resource such as this cannot be underestimated. Remember, if you can’t find out where your branch of the family came from in Ireland; go to the branch which went to Australia and New Zealand. Chances are their records will provide birth places. The AGCI provides easy access to records which are important for these types of research strategies.
The current edition of the AGCI on CD-ROM (2004) includes some 3.9 million records indexed by 39 societies. A second CD (2005) contains entries extracted from the New South Wales Government Gazette(1832-1863). Other CDs are planned for the AGCI. The AGCI will provide the individual’s name, place, date, cross reference, type of record (church, cemetery, government, newspaper, etc.), and the society which submitted the entry. This is a resource worth studying or purchasing for a library with genealogical collections.
If you find an index entry of interest then either look for the original record on microfilm at the Family History Library: www.familysearch.org or contact the SAG which has a record retrieval department for sources at the SAG Library, National Library of Australia, and from State Records of New South Wales. These entries comprise about two-thirds of the first AGCI CD and all of the second volume. Otherwise, the individual society which submitted the entry will need to be contacted directly.
This type of research is thinking outside the box.