A red letter day for Irish researchers with over 24 million records added at Ancestry.co.uk and to other World Deluxe subscriptions.
These index entries contain name, year of the event , volume and page number. For births the mother's maiden name is given after 1903, For deaths age at death is included. The full certificates can be purchased from the GROs in Ireland and North Ireland as appropriate.
This is a miscellaneous collection of extractions from "a variety of Irish birth records" extracted by volunteers. Details in the entries vary depending on the original record.
Ireland, Catholic Parish Deaths, 1756-1881 29,644
Although the Ancestry description refers to these as indexed images I found the images elusive, just extracted information for the sample I checked. My impression is that coverage is particularly good for Meath.
Check FamilySearch.org for their version of the Irish civil registration indexes before going out of your way to find or pay for the Ancestry version.
Chris Paton has some further observations at http://goo.gl/UMVu5